isci: Converting smp_response to Linux native smp_resp

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/scsi/isci/sas.h b/drivers/scsi/isci/sas.h
index f5d7e6a..83eab46 100644
--- a/drivers/scsi/isci/sas.h
+++ b/drivers/scsi/isci/sas.h
@@ -213,4 +213,6 @@
 	};
 }  __packed;
 
+#define SMP_RESP_HDR_SZ	4
+
 #endif