net/mlx5: DR, Modify set action limitation extension

Modify set actions are not supported on both tx
and rx, added a check for that.
Also refactored the code in a way that every modify
action has his own functions, this needed so in the
future we could add copy action more smoothly.

Signed-off-by: Hamdan Igbaria <hamdani@mellanox.com>
Signed-off-by: Alex Vesker <valex@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>