temporarily hardcode Nexus S refresh rate

Change-Id: Id8465f679b96636041b4b891d0b358c387d456c3
diff --git a/services/surfaceflinger/Android.mk b/services/surfaceflinger/Android.mk
index 61a8358..f63c0c1 100644
--- a/services/surfaceflinger/Android.mk
+++ b/services/surfaceflinger/Android.mk
@@ -28,6 +28,7 @@
 endif
 ifeq ($(TARGET_BOARD_PLATFORM), s5pc110)
 	LOCAL_CFLAGS += -DHAS_CONTEXT_PRIORITY -DNEVER_DEFAULT_TO_ASYNC_MODE
+	LOCAL_CFLAGS += -DREFRESH_RATE=56
 endif