IB/rdmavt: Add support for rvt_query_qp

Drivers using rdmavt can rely on rvt_query_qp instead of defining their own
query_qp functions.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>