RDMA/siw: Simplify QP representation

Change siw_qp to contain ib_qp. Use rdma_is_kernel_res() on contained
ib_qp to distinguish kernel level from user level applications
resources. Apply same mechanism for kernel/user level application
detection to completion queues.

Link: https://lore.kernel.org/r/20191210161729.31598-1-bmt@zurich.ibm.com


Signed-off-by: Bernard Metzler <bmt@zurich.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>