iwlwifi: do not re-configure HT40 after associated

The ht40 setting should not change after association unless channel switch

This fix a problem we are seeing which cause uCode assert because driver
sending invalid information and make uCode confuse

Here is the firmware assert message:
kernel: iwlagn 0000:03:00.0: Microcode SW error detected.  Restarting 0x82000000.
kernel: iwlagn 0000:03:00.0: Loaded firmware version: 17.168.5.3 build 42301
kernel: iwlagn 0000:03:00.0: Start IWL Error Log Dump:
kernel: iwlagn 0000:03:00.0: Status: 0x000512E4, count: 6
kernel: iwlagn 0000:03:00.0: 0x00002078 | ADVANCED_SYSASSERT
kernel: iwlagn 0000:03:00.0: 0x00009514 | uPc
kernel: iwlagn 0000:03:00.0: 0x00009496 | branchlink1
kernel: iwlagn 0000:03:00.0: 0x00009496 | branchlink2
kernel: iwlagn 0000:03:00.0: 0x0000D1F2 | interruptlink1
kernel: iwlagn 0000:03:00.0: 0x00000000 | interruptlink2
kernel: iwlagn 0000:03:00.0: 0x01008035 | data1
kernel: iwlagn 0000:03:00.0: 0x0000C90F | data2
kernel: iwlagn 0000:03:00.0: 0x000005A7 | line
kernel: iwlagn 0000:03:00.0: 0x5080B520 | beacon time
kernel: iwlagn 0000:03:00.0: 0xCC515AE0 | tsf low
kernel: iwlagn 0000:03:00.0: 0x00000003 | tsf hi
kernel: iwlagn 0000:03:00.0: 0x00000000 | time gp1
kernel: iwlagn 0000:03:00.0: 0x29703BF0 | time gp2
kernel: iwlagn 0000:03:00.0: 0x00000000 | time gp3
kernel: iwlagn 0000:03:00.0: 0x000111A8 | uCode version
kernel: iwlagn 0000:03:00.0: 0x000000B0 | hw version
kernel: iwlagn 0000:03:00.0: 0x00480303 | board version
kernel: iwlagn 0000:03:00.0: 0x09E8004E | hcmd
kernel: iwlagn 0000:03:00.0: CSR values:
kernel: iwlagn 0000:03:00.0: (2nd byte of CSR_INT_COALESCING is CSR_INT_PERIODIC_REG)
kernel: iwlagn 0000:03:00.0:        CSR_HW_IF_CONFIG_REG: 0X00480303
kernel: iwlagn 0000:03:00.0:          CSR_INT_COALESCING: 0X0000ff40
kernel: iwlagn 0000:03:00.0:                     CSR_INT: 0X00000000
kernel: iwlagn 0000:03:00.0:                CSR_INT_MASK: 0X00000000
kernel: iwlagn 0000:03:00.0:           CSR_FH_INT_STATUS: 0X00000000
kernel: iwlagn 0000:03:00.0:                 CSR_GPIO_IN: 0X00000030
kernel: iwlagn 0000:03:00.0:                   CSR_RESET: 0X00000000
kernel: iwlagn 0000:03:00.0:                CSR_GP_CNTRL: 0X080403c5
kernel: iwlagn 0000:03:00.0:                  CSR_HW_REV: 0X000000b0
kernel: iwlagn 0000:03:00.0:              CSR_EEPROM_REG: 0X07d60ffd
kernel: iwlagn 0000:03:00.0:               CSR_EEPROM_GP: 0X90000001
kernel: iwlagn 0000:03:00.0:              CSR_OTP_GP_REG: 0X00030001
kernel: iwlagn 0000:03:00.0:                 CSR_GIO_REG: 0X00080044
kernel: iwlagn 0000:03:00.0:            CSR_GP_UCODE_REG: 0X000093bb
kernel: iwlagn 0000:03:00.0:           CSR_GP_DRIVER_REG: 0X00000000
kernel: iwlagn 0000:03:00.0:           CSR_UCODE_DRV_GP1: 0X00000000
kernel: iwlagn 0000:03:00.0:           CSR_UCODE_DRV_GP2: 0X00000000
kernel: iwlagn 0000:03:00.0:                 CSR_LED_REG: 0X00000078
kernel: iwlagn 0000:03:00.0:        CSR_DRAM_INT_TBL_REG: 0X88214dd2
kernel: iwlagn 0000:03:00.0:        CSR_GIO_CHICKEN_BITS: 0X27800200
kernel: iwlagn 0000:03:00.0:             CSR_ANA_PLL_CFG: 0X00000000
kernel: iwlagn 0000:03:00.0:           CSR_HW_REV_WA_REG: 0X0001001a
kernel: iwlagn 0000:03:00.0:        CSR_DBG_HPET_MEM_REG: 0Xffff0010
kernel: iwlagn 0000:03:00.0: FH register values:
kernel: iwlagn 0000:03:00.0:         FH_RSCSR_CHNL0_STTS_WPTR_REG: 0X21316d00
kernel: iwlagn 0000:03:00.0:        FH_RSCSR_CHNL0_RBDCB_BASE_REG: 0X021479c0
kernel: iwlagn 0000:03:00.0:                  FH_RSCSR_CHNL0_WPTR: 0X00000060
kernel: iwlagn 0000:03:00.0:         FH_MEM_RCSR_CHNL0_CONFIG_REG: 0X80819104
kernel: iwlagn 0000:03:00.0:          FH_MEM_RSSR_SHARED_CTRL_REG: 0X000000fc
kernel: iwlagn 0000:03:00.0:            FH_MEM_RSSR_RX_STATUS_REG: 0X07030000
kernel: iwlagn 0000:03:00.0:    FH_MEM_RSSR_RX_ENABLE_ERR_IRQ2DRV: 0X00000000
kernel: iwlagn 0000:03:00.0:                FH_TSSR_TX_STATUS_REG: 0X07ff0001
kernel: iwlagn 0000:03:00.0:                 FH_TSSR_TX_ERROR_REG: 0X00000000
kernel: iwlagn 0000:03:00.0: Start IWL Event Log Dump: display last 20 entries
kernel: ------------[ cut here ]------------
WARNING: at net/mac80211/util.c:1208 ieee80211_reconfig+0x1f1/0x407()
kernel: Hardware name: 4290W4H
kernel: Pid: 1896, comm: kworker/0:0 Not tainted 3.1.0 #2
kernel: Call Trace:
kernel:  [<ffffffff81036558>] ? warn_slowpath_common+0x73/0x87
kernel:  [<ffffffff813b8966>] ? ieee80211_reconfig+0x1f1/0x407
kernel:  [<ffffffff8139e8dc>] ? ieee80211_recalc_smps_work+0x32/0x32
kernel:  [<ffffffff8139e95a>] ? ieee80211_restart_work+0x7e/0x87
kernel:  [<ffffffff810472fa>] ? process_one_work+0x1c8/0x2e3
kernel:  [<ffffffff810480c9>] ? worker_thread+0x17a/0x23a
kernel:  [<ffffffff81047f4f>] ? manage_workers.clone.18+0x15b/0x15b
kernel:  [<ffffffff81047f4f>] ? manage_workers.clone.18+0x15b/0x15b
kernel:  [<ffffffff8104ba97>] ? kthread+0x7a/0x82
kernel:  [<ffffffff813d21b4>] ? kernel_thread_helper+0x4/0x10
kernel:  [<ffffffff8104ba1d>] ? kthread_flush_work_fn+0x11/0x11
kernel:  [<ffffffff813d21b0>] ? gs_change+0xb/0xb

Cc: <stable@kernel.org> 3.1+
Reported-by: Udo Steinberg <udo@hypervisor.org>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>