net/mlx5e: Support VLAN modify action

Support VLAN modify action by emulating a rewrite action for the VLAN
fields. Currently, the only supported field is the vid. The prio in the
action must be set to 0 to indicate no change.

Signed-off-by: Eli Britstein <elibr@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>