net/mlx5: DR, Add the internal direct rule types definitions

Add the internal header file that contains various types
definition that will be used in coming patches as well as
the internal functions decelerations.

Signed-off-by: Alex Vesker <[email protected]>
Signed-off-by: Yevgeny Kliteynik <[email protected]>
Reviewed-by: Erez Shitrit <[email protected]>
Reviewed-by: Mark Bloch <[email protected]>
Signed-off-by: Saeed Mahameed <[email protected]>

Author: alexvesker