i40e: fix broken i40e_config_rss_aq function

X722 hardware requires using the admin queue to configure RSS. This
function was previously re-written in commit e69ff813 ("i40e: rework
the functions to configure RSS with similar parameters").
However, the previous refactor did not work correctly for a few reasons

(a) it does not check whether seed is NULL before using it, resulting in
a NULL pointer dereference

[  402.954721] BUG: unable to handle kernel NULL pointer dereference at           (null)
[  402.955568] IP: [<ffffffffa0090ccf>] i40e_config_rss_aq.constprop.65+0x2f/0x1c0 [i40e]
[  402.956402] PGD ad610067 PUD accc0067 PMD 0
[  402.957235] Oops: 0000 [#1] SMP
[  402.958064] Modules linked in: ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 xt_conntrack ip_set nfnetlink ebtable_filter ebtable_
broute bridge stp llc ebtable_nat ebtables ip6table_mangle ip6table_raw ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv
6 ip6table_security ip6table_filter ip6_tables iptable_mangle iptable_raw iptable_nat nf_conntrack_ipv4_ nf_defrag_ipv4_ nf_nat_ip
v4_ nf_nat nf_conntrack iptable_security intel_rapl i86_kg_temp_thermal coretemp kvm_intel kvm irqbypass crct10dif_clMl crc32_
pclMl ghash_clMlni_intel iTCO_wdt iTCO_vendor_support shpchp sb_edac dcdbas pcspkr joydev ipmi_devintf wmi edac_core ipmi_ssif
 acpi_ad acpi_ower_meter ipmi_si ipmi_msghandler mei_me nfsd lpc_ich mei ioatdma tpm_tis auth_rpcgss tpm nfs_acl lockd grace s
unrpc ifs nngag200 i2c_algo_bit drm_kms_helper ttm drm iigbe bnx2x i40e dca mdio ptp pps_core libcrc32c fjes crc32c_intel
[  402.965563] CPU: 22 PID: 2461 Conm: ethtool Not tainted 4.6.0-rc7_1.2-ABNidQ+ #20
[  402.966719] Hardware name: Dell Inc. PowerEdge R720/0C4Y3R, BIOS 2.5.2 01/28/2015
[  402.967862] task: ffff880219b51dc0 ti: ffff8800b3408000 task.ti: ffff8800b3408000
[  402.969046] RIP: 0010:[<ffffffffa0090ccf>]  [<ffffffffa0090ccf>] i40e_config_rss_aq.constprop.65+0x2f/0x1c0 [i40e]
[  402.970339] RSP: 0018:ffff8800b340ba90  EFLAGS: 00010246
[  402.971616] RAX: 0000000000000000 RBX: ffff88042ec14000 RCX: 0000000000000200
[  402.972961] RDX: ffff880428eb9200 RSI: 0000000000000000 RDI: ffff88042ec14000
[  402.974312] RBP: ffff8800b340baf8 R08: ffff880237ada8f0 R09: ffff880428eb9200
[  402.975709] R10: ffff880428eb9200 R11: 0000000000000000 R12: ffff88042ec2e000
[  402.977104] R13: ffff88042ec2e000 R14: ffff88042ec14000 R15: ffff88022ea00800
[  402.978541] FS:  00007f84fd054700(0000) GS:ffff880237ac0000(0000) knlGS:0000000000000000
[  402.980003] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  402.981508] CR2: 0000000000000000 CR3: 000000003289e000 CR4: 00000000000406e0
[  402.983028] Stack:
[  402.984578]  0000000002000200 0000000000000000 ffff88023ffeda68 ffff88023ffef000
[  402.986187]  0000000000000268 ffff8800b340bbf8 ffff88023ffedd80 0000000088ce4f1d
[  402.987844]  ffff88042ec14000 ffff88022ea00800 ffff88042ec2e000 ffff88042ec14000
[  402.989509] Call Trace:
[  402.991200]  [<ffffffffa009636f>] i40e_config_rss+0x11f/0x1c0 [i40e]
[  402.992924]  [<ffffffffa00a1ae0>] i40e_set_rifh+0ic0/0x130 [i40e]
[  402.994684]  [<ffffffff816d54b7>] ethtool_set_rifh+0x1f7/0x300
[  402.996446]  [<ffffffff8136d02b>] ? cred_has_capability+0io6b/0x100
[  402.998203]  [<ffffffff8136d102>] ? selinux_capable+0x12/0x20
[  402.999968]  [<ffffffff8136277b>] ? security_capable+0x4b/0x70
[  403.001707]  [<ffffffff816d6da3>] dev_ethtool+0x1423/0x2290
[  403.003461]  [<ffffffff816eab41>] dev_ioctl+0x191/0io630
[  403.005186]  [<ffffffff811cf80a>] ? lru_cache_add+0x3a/0i80
[  403.006942]  [<ffffffff817f2a8e>] ? _raw_spin_unlock+0ie/0x20
[  403.008691]  [<ffffffff816adb95>] sock_do_ioctl+0x45/0i50
[  403.010421]  [<ffffffff816ae229>] sock_ioctl+0x209/0x2d0
[  403.012173]  [<ffffffff81262194>] do_vfs_ioctl+0u4/0io6c0
[  403.013911]  [<ffffffff81262829>] SyS_ioctl+0x79/0x90
[  403.015710]  [<ffffffff817f2e72>] entry_SYSCALL_64_fastpath+0x1a/0u4
[  403.017500] Code: 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 89 fb 48 83 ec 40 4c 8b a7 e0 05 00 00 65 48 8b 04 25 28 00 00 00 48 89 45 d0 31 c0 <48> 8b 06 41 0f b7 bc 24 f2 0f 00 00 48 89 45 9c 48 8b 46 08 48
[  403.021454] RIP  [<ffffffffa0090ccf>] i40e_config_rss_aq.constprop.65+0x2f/0x1c0 [i40e]
[  403.023395]  RSP <ffff8800b340ba90>
[  403.025271] CR2: 0000000000000000
[  403.027169] ---[ end trace 64561b528cf61cf0 ]---

(b) it does not even bother to use the passed in *lut parameter which
defines the requested lookup table. Instead it uses its own round robin
table.

Fix these issues by re-writing it to be similar to i40e_config_rss_reg
and i40e_get_rss_aq.

Fixes: e69ff813 ("i40e: rework the functions to configure RSS with similar parameters", 2015-10-21)
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>