net/mlx5: Lag, Fix recreation of VF LAG

Driver needs to nullify the port select attributes of the LAG when
port selection is destroyed, otherwise it breaks recreation of the
LAG.
It fixes the below kernel oops:

 [  587.906377] BUG: kernel NULL pointer dereference, address: 0000000000000008
 [  587.908843] #PF: supervisor read access in kernel mode
 [  587.910730] #PF: error_code(0x0000) - not-present page
 [  587.912580] PGD 0 P4D 0
 [  587.913632] Oops: 0000 [#1] SMP PTI
 [  587.914644] CPU: 5 PID: 165 Comm: kworker/u20:5 Tainted: G           OE     5.9.0_mlnx #1
 [  587.916152] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
 [  587.918332] Workqueue: mlx5_lag mlx5_do_bond_work [mlx5_core]
 [  587.919479] RIP: 0010:mlx5_del_flow_rules+0x10/0x270 [mlx5_core]
 [  587.920568] mlx5_core 0000:08:00.1 enp8s0f1: Link up
 [  587.920680] Code: c0 09 80 a0 e8 cf 42 a4 e0 48 c7 c3 f4 ff ff ff e8 8a 88 dd e0 e9 ab fe ff ff 0f 1f 44 00 00 41 56 41 55 49 89 fd 41 54 55 53 <48> 8b 47 08 48 8b 68 28 48 85 ed 74 2e 48 8d 7d 38 e8 6a 64 34 e1
 [  587.925116] bond0: (slave enp8s0f1): Enslaving as an active interface with an up link
 [  587.930415] RSP: 0018:ffffc9000048fd88 EFLAGS: 00010282
 [  587.930417] RAX: ffff88846c14fac0 RBX: ffff88846cddcb80 RCX: 0000000080400007
 [  587.930417] RDX: 0000000080400008 RSI: ffff88846cddcb80 RDI: 0000000000000000
 [  587.930419] RBP: ffff88845fd80140 R08: 0000000000000001 R09: ffffffffa074ba00
 [  587.938132] R10: ffff88846c14fec0 R11: 0000000000000001 R12: ffff88846c122f10
 [  587.939473] R13: 0000000000000000 R14: 0000000000000001 R15: ffff88846d7a0000
 [  587.940800] FS:  0000000000000000(0000) GS:ffff88846fa80000(0000) knlGS:0000000000000000
 [  587.942416] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 [  587.943536] CR2: 0000000000000008 CR3: 000000000240a002 CR4: 0000000000770ee0
 [  587.944904] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 [  587.946308] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 [  587.947639] PKRU: 55555554
 [  587.948236] Call Trace:
 [  587.948834]  mlx5_lag_destroy_definer.isra.3+0x16/0x90 [mlx5_core]
 [  587.950033]  mlx5_lag_destroy_definers+0x5b/0x80 [mlx5_core]
 [  587.951128]  mlx5_deactivate_lag+0x6e/0x80 [mlx5_core]
 [  587.952146]  mlx5_do_bond+0x150/0x450 [mlx5_core]
 [  587.953086]  mlx5_do_bond_work+0x3e/0x50 [mlx5_core]
 [  587.954086]  process_one_work+0x1eb/0x3e0
 [  587.954899]  worker_thread+0x2d/0x3c0
 [  587.955656]  ? process_one_work+0x3e0/0x3e0
 [  587.956493]  kthread+0x115/0x130
 [  587.957174]  ? kthread_park+0x90/0x90
 [  587.957929]  ret_from_fork+0x1f/0x30
 [  587.973055] ---[ end trace 71ccd6eca89f5513 ]---

Fixes: b7267869

 ("net/mlx5: Lag, add support to create/destroy/modify port selection")
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>