net/mlx5: Introduce migration bits and structures

Introduce migration IFC related stuff to enable migration commands.

Link: https://lore.kernel.org/all/20220224142024.147653-7-yishaih@nvidia.com


Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>