Change BUILD_ID.

On master branch build id should be MASTER.

Change-Id: I7829b3933947730b298fca8a4e39de6a60b9caad
diff --git a/core/build_id.mk b/core/build_id.mk
index 6da16e0..40bb35d 100644
--- a/core/build_id.mk
+++ b/core/build_id.mk
@@ -23,7 +23,7 @@
 # (like "TC1-RC5").  It must be a single word, and is
 # capitalized by convention.
 #
-BUILD_ID := ICS_MR0
+BUILD_ID := MASTER
 
 # DISPLAY_BUILD_NUMBER should only be set for development branches,
 # If set, the BUILD_NUMBER (cl) is appended to the BUILD_ID for