net/mlx5: Add core support for double vlan push/pop steering action

As newer firmware supports double push/pop in a single FTE, we add
core bits and extend vlan action logic for it.

Signed-off-by: Jianbo Liu <jianbol@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>