IB/qib: Decode path MTU optimization

Store both the encoded and decoded MTU in the QP structure as a minor
optimization for UC/RC receive routines.

Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/drivers/infiniband/hw/qib/qib_qp.c b/drivers/infiniband/hw/qib/qib_qp.c
index e16751f..9d094f9 100644
--- a/drivers/infiniband/hw/qib/qib_qp.c
+++ b/drivers/infiniband/hw/qib/qib_qp.c
@@ -765,8 +765,10 @@
 		}
 	}
 
-	if (attr_mask & IB_QP_PATH_MTU)
+	if (attr_mask & IB_QP_PATH_MTU) {
 		qp->path_mtu = pmtu;
+		qp->pmtu = ib_mtu_enum_to_int(pmtu);
+	}
 
 	if (attr_mask & IB_QP_RETRY_CNT) {
 		qp->s_retry_cnt = attr->retry_cnt;