net/mlx5: DR, Add direct rule command utilities

Add direct rule command utilities which consists of all the FW
commands that are executed to provide the SW steering functionality.

Signed-off-by: Alex Vesker <valex@mellanox.com>
Reviewed-by: Erez Shitrit <erezsh@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>