IB/hfi1: Add functions for restarting TID RDMA READ request

This patch adds functions to retry TID RDMA READ request. Since TID RDMA
READ request could be retried from any segment boundary, it requires
a number of tracking fields in various structures and those fields
should be reset properly. The qp->s_num_rd_atomic field is reset before
retry and therefore should be incremented for each new or retried
RDMA READ or atomic request.

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