IB/hfi1: Report pid in qp_stats to aid debug

Tracking user/QP ownership is needed to debug issues with
user ULPs like OpenMPI.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>