Fix warning in reference ril

Bug: None
Test: mma
Change-Id: I899adb43c908aefb0bf9cd1c34a3faa16fe1c185
diff --git a/reference-ril/reference-ril.c b/reference-ril/reference-ril.c
index d1c4455..9b9c624 100644
--- a/reference-ril/reference-ril.c
+++ b/reference-ril/reference-ril.c
@@ -1750,7 +1750,7 @@
     }
 
     cmd_size = 10 + (apdu->data ? strlen(apdu->data) : 0);
-    asprintf(&cmd, "AT+CGLA=%d,%d,%02x%02x%02x%02x%02x%s",
+    asprintf(&cmd, "AT+CGLA=%d,%zu,%02x%02x%02x%02x%02x%s",
              apdu->sessionid, cmd_size, apdu->cla, apdu->instruction,
              apdu->p1, apdu->p2, apdu->p3, apdu->data ? apdu->data : "");