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_rc.c b/drivers/infiniband/hw/qib/qib_rc.c
index 5c1c49b..5d77cb8 100644
--- a/drivers/infiniband/hw/qib/qib_rc.c
+++ b/drivers/infiniband/hw/qib/qib_rc.c
@@ -239,7 +239,7 @@
 	u32 len;
 	u32 bth0;
 	u32 bth2;
-	u32 pmtu = ib_mtu_enum_to_int(qp->path_mtu);
+	u32 pmtu = qp->pmtu;
 	char newreq;
 	unsigned long flags;
 	int ret = 0;
@@ -1732,7 +1732,7 @@
 		 * same request.
 		 */
 		offset = ((psn - e->psn) & QIB_PSN_MASK) *
-			ib_mtu_enum_to_int(qp->path_mtu);
+			qp->pmtu;
 		len = be32_to_cpu(reth->length);
 		if (unlikely(offset + len != e->rdma_sge.sge_length))
 			goto unlock_done;
@@ -1876,7 +1876,7 @@
 	u32 psn;
 	u32 pad;
 	struct ib_wc wc;
-	u32 pmtu = ib_mtu_enum_to_int(qp->path_mtu);
+	u32 pmtu = qp->pmtu;
 	int diff;
 	struct ib_reth *reth;
 	unsigned long flags;