gralloc/metadata: Add support for single buffer mode

Add support for setting single buffer mode on a buffer via gralloc
perform from gfx

Change-Id: I7640b3b984ebc1c4c8fcaedfb3e222ec989a84cb
diff --git a/libgralloc/gralloc_priv.h b/libgralloc/gralloc_priv.h
index 38a6235..efc7d67 100644
--- a/libgralloc/gralloc_priv.h
+++ b/libgralloc/gralloc_priv.h
@@ -88,6 +88,7 @@
 #define GRALLOC_MODULE_PERFORM_GET_RGB_DATA_ADDRESS 10
 #define GRALLOC_MODULE_PERFORM_GET_IGC 11
 #define GRALLOC_MODULE_PERFORM_SET_IGC 12
+#define GRALLOC_MODULE_PERFORM_SET_SINGLE_BUFFER_MODE 13
 
 /* OEM specific HAL formats */