net/mlx5e: Fix crash unsetting rx-vlan-filter in switchdev mode

Moving to switchdev mode with rx-vlan-filter on and then setting it off
causes the kernel to crash since fs->vlan is freed during nic profile
cleanup flow.

RX VLAN filtering is not supported in switchdev mode so unset it when
changing to switchdev and restore its value when switching back to
legacy.

trace:
[] RIP: 0010:mlx5e_disable_cvlan_filter+0x43/0x70
[] set_feature_cvlan_filter+0x37/0x40 [mlx5_core]
[] mlx5e_handle_feature+0x3a/0x60 [mlx5_core]
[] mlx5e_set_features+0x6d/0x160 [mlx5_core]
[] __netdev_update_features+0x288/0xa70
[] ethnl_set_features+0x309/0x380
[] ? __nla_parse+0x21/0x30
[] genl_family_rcv_msg_doit.isra.17+0x110/0x150
[] genl_rcv_msg+0x112/0x260
[] ? features_reply_size+0xe0/0xe0
[] ? genl_family_rcv_msg_doit.isra.17+0x150/0x150
[] netlink_rcv_skb+0x4e/0x100
[] genl_rcv+0x24/0x40
[] netlink_unicast+0x1ab/0x290
[] netlink_sendmsg+0x257/0x4f0
[] sock_sendmsg+0x5c/0x70

Fixes: cb67b832

 ("net/mlx5e: Introduce SRIOV VF representors")
Signed-off-by: Amir Tzin <amirtz@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>