IB/mlx5: Avoid passing an invalid QP type to firmware

During QP creation, the mlx5 driver translates the QP type to an
internal value which is passed on to FW. There was no check to make
sure that the translated value is valid, and -EINVAL was coerced into
the mailbox command.

Current firmware refuses this as an invalid QP type, but future/past
firmware may do something else.

Fixes: 09a7d9ec ('{net,IB}/mlx5: QP/XRCD commands via mlx5 ifc')
Reviewed-by: Ilya Lesokhin <ilyal@mellanox.com>
Signed-off-by: Noa Osherovich <noaos@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>