RDMA/mlx5: Fix query DCT via DEVX

When executing DEVX command to query QP object, we need to take the QP
type from the mlx5_ib_qp struct which hold the driver specific QP types as
well, such as DC.

Fixes: 34613eb1 ("IB/mlx5: Enable modify and query verbs objects via DEVX")
Link: https://lore.kernel.org/r/6eee15d63f09bb70787488e0cf96216e2957f5aa.1621413654.git.leonro@nvidia.com


Reviewed-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>