ice: fix crash in switchdev mode

Below steps end up with crash:
- modprobe ice
- devlink dev eswitch set $PF1_PCI mode switchdev
- echo 64 > /sys/class/net/$PF1/device/sriov_numvfs
- rmmod ice

Calling ice_eswitch_port_start_xmit while the process of removing
VFs is in progress ends up with NULL pointer dereference.
That's because PR netdev is not released but some resources
are already freed. Fix it by checking if ICE_VF_DIS bit is set.

Call trace:
[ 1379.595146] BUG: kernel NULL pointer dereference, address: 0000000000000040
[ 1379.595284] #PF: supervisor read access in kernel mode
[ 1379.595410] #PF: error_code(0x0000) - not-present page
[ 1379.595535] PGD 0 P4D 0
[ 1379.595657] Oops: 0000 [#1] PREEMPT SMP PTI
[ 1379.595783] CPU: 4 PID: 974 Comm: NetworkManager Kdump: loaded Tainted: G           OE     5.17.0-rc8_mrq_dev-queue+ #12
[ 1379.595926] Hardware name: Intel Corporation S1200SP/S1200SP, BIOS S1200SP.86B.03.01.0042.013020190050 01/30/2019
[ 1379.596063] RIP: 0010:ice_eswitch_port_start_xmit+0x46/0xd0 [ice]
[ 1379.596292] Code: c7 c8 09 00 00 e8 9a c9 fc ff 84 c0 0f 85 82 00 00 00 4c 89 e7 e8 ca 70 fe ff 48 8b 7d 58 48 89 c3 48 85 ff 75 5e 48 8b 53 20 <8b> 42 40 85 c0 74 78 8d 48 01 f0 0f b1 4a 40 75 f2 0f b6 95 84 00
[ 1379.596456] RSP: 0018:ffffaba0c0d7bad0 EFLAGS: 00010246
[ 1379.596584] RAX: ffff969c14c71680 RBX: ffff969c14c71680 RCX: 000100107a0f0000
[ 1379.596715] RDX: 0000000000000000 RSI: ffff969b9d631000 RDI: 0000000000000000
[ 1379.596846] RBP: ffff969c07b46500 R08: ffff969becfca8ac R09: 0000000000000001
[ 1379.596977] R10: 0000000000000004 R11: ffffaba0c0d7bbec R12: ffff969b9d631000
[ 1379.597106] R13: ffffffffc08357a0 R14: ffff969c07b46500 R15: ffff969b9d631000
[ 1379.597237] FS:  00007f72c0e25c80(0000) GS:ffff969f13500000(0000) knlGS:0000000000000000
[ 1379.597414] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1379.597562] CR2: 0000000000000040 CR3: 000000012b316006 CR4: 00000000003706e0
[ 1379.597713] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1379.597863] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 1379.598015] Call Trace:
[ 1379.598153]  <TASK>
[ 1379.598294]  dev_hard_start_xmit+0xd9/0x220
[ 1379.598444]  sch_direct_xmit+0x8a/0x340
[ 1379.598592]  __dev_queue_xmit+0xa3c/0xd30
[ 1379.598739]  ? packet_parse_headers+0xb4/0xf0
[ 1379.598890]  packet_sendmsg+0xa15/0x1620
[ 1379.599038]  ? __check_object_size+0x46/0x140
[ 1379.599186]  sock_sendmsg+0x5e/0x60
[ 1379.599330]  ____sys_sendmsg+0x22c/0x270
[ 1379.599474]  ? import_iovec+0x17/0x20
[ 1379.599622]  ? sendmsg_copy_msghdr+0x59/0x90
[ 1379.599771]  ___sys_sendmsg+0x81/0xc0
[ 1379.599917]  ? __pollwait+0xd0/0xd0
[ 1379.600061]  ? preempt_count_add+0x68/0xa0
[ 1379.600210]  ? _raw_write_lock_irq+0x1a/0x40
[ 1379.600369]  ? ep_done_scan+0xc9/0x110
[ 1379.600494]  ? _raw_spin_unlock_irqrestore+0x25/0x40
[ 1379.600622]  ? preempt_count_add+0x68/0xa0
[ 1379.600747]  ? _raw_spin_lock_irq+0x1a/0x40
[ 1379.600899]  ? __fget_light+0x8f/0x110
[ 1379.601024]  __sys_sendmsg+0x49/0x80
[ 1379.601148]  ? release_ds_buffers+0x50/0xe0
[ 1379.601274]  do_syscall_64+0x3b/0x90
[ 1379.601399]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 1379.601525] RIP: 0033:0x7f72c1e2e35d

Fixes: f5396b8a

 ("ice: switchdev slow path")
Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Reported-by: Marcin Szycik <marcin.szycik@linux.intel.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>