IB/hfi1: Compute BTH only for RDMA_WRITE_LAST/SEND_LAST packet

In hfi1_rc_rcv(), BTH is computed for all packets received.
However, it's only used for packets received with opcodes
RDMA_WRITE_LAST and SEND_LAST, and it is a costly operation.

Compute BTH only in the RDMA_WRITE_LAST/SEND_LAST code path
and let the compiler handle endianness conversion for bitwise
operations.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Sebastian Sanchez <sebastian.sanchez@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/qib/qib_uc.c

@@ -403,8 +403,7 @@ last_imm:
 		wc.port_num = 0;
 		/* Signal completion event if the solicited bit is set. */
 		rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.recv_cq), &wc,
-			     (ohdr->bth[0] &
-				cpu_to_be32(IB_BTH_SOLICITED)) != 0);
+			     ib_bth_is_solicited(ohdr));
 		break;
 
 	case OP(RDMA_WRITE_FIRST):