net/mlx5: fix check for VLAN actions

net/mlx5: fix check for VLAN actions

Flow validation function includes, after all items and actions are
validated discretely, a check for VLAN and VXLAN actions.
This check is incorrect and redundant.

This patch removes the invalid check from validation function.
Check is incorrect, action_flags bit map is checked against
items mask MLX5_FLOW_LAYER_TUNNEL.
Check is also redundant, because VLAN push/pop actions can be used
together with packet reformat actions.

Fixes: b41e47da2592 ("net/mlx5: support pop flow action on VLAN header")
Cc: stable@dpdk.org
Signed-off-by: Dekel Peled <dekelp@mellanox.com>
Acked-by: Ori Kam <orika@mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>