IB/mlx5: Add support for QP with a given source QPN

Allow user space applications to accelerate send and receive
traffic which is typically handled by IPoIB ULP by creating
a UD QP with a given source QPN of the IPoIB UD QP.

UD QP with a given source QPN should basically be similar to
RAW QP from point of view of its created resources.

However,
- Its TIS should point to the source QPN.
- Modify can be done only on its state as the transport attributes
  are managed by its source QP.

This patch manages below:
- Creating/destroying/modifying UD QP with a given source QPN.

Signed-off-by: Yishai Hadas <yishaih@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>