net/mlx5e: Split actions_match_supported() into a sub function

There will probably be more checks, some for nic flows, some for fdb
flows and some are shared checks. Split it for fdb and nic to avoid
the function getting too big.

Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>