[SCSI] ibmvfc: Fix errors due to inconsistent command data

In order to ensure the VIOS sees a consistent command buffer, we
need to add a memory barrier after building the command buffer
but before sending the command.
Signed-off-by: NBrian King <brking@linux.vnet.ibm.com>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/ibmvscsi/ibmvfc.c

@@ -1381,6 +1381,8 @@ static int ibmvfc_send_event(struct ibmvfc_event *evt,
 		add_timer(&evt->timer);
 	}
 
+	mb();
+
 	if ((rc = ibmvfc_send_crq(vhost, crq_as_u64[0], crq_as_u64[1]))) {
 		list_del(&evt->queue);
 		del_timer(&evt->timer);