staging/rdma/hfi1: Allow a fair scheduling of QPs

This patch fixes the fairness issues in QP scheduling
- the timeout for cond_resched is changed to a ratio of
qp->timeout_jiffies
- workqueue_congested is used to determine if qp needs to
reschedule itself

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Vennila Megavannan <vennila.megavannan@intel.com>
Signed-off-by: Jubin John <jubin.john@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>