IB/rdmavt: No need to cancel RNRNAK retry timer when it is running

When the rdmavt's RNRNAK timer is fired, it tries to cancel the timer by
calling hrtimer_try_to_cancel(), which always returns -1 because the timer
is currently running. This patch removes this useless call.
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>

drivers/infiniband/sw/rdmavt/qp.c

@@ -2110,10 +2110,8 @@ static int rvt_stop_rnr_timer(struct rvt_qp *qp)
 
 	lockdep_assert_held(&qp->s_lock);
 	/* Remove QP from rnr timer */
-	if (qp->s_flags & RVT_S_WAIT_RNR) {
+	if (qp->s_flags & RVT_S_WAIT_RNR)
 		qp->s_flags &= ~RVT_S_WAIT_RNR;
-		rval = hrtimer_try_to_cancel(&qp->s_rnr_timer);
-	}
 	return rval;
 }