NuMaker without external SRAM configuration

Revision:
1:a3b9047e5ae0
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed_app.json	Wed Mar 01 13:03:04 2017 +0800
@@ -0,0 +1,8 @@
+{
+    "target_overrides": {
+        "NUMAKER_PFM_NUC472": {
+            "target.extra_labels_remove": ["NU_XRAM_SUPPORTED"],
+            "target.extra_labels_add": ["NU_XRAM_UNSUPPORTED"]
+        }
+    }
+}
\ No newline at end of file