Restore the original Makfile content and rely on patch to fix compiling issue.

Change-Id: I1955184ed6fb0feccfacb40a8fbae2b21b1a0844
diff --git a/Makefile b/Makefile
index aa2f10633..2c287e1 100755
--- a/Makefile
+++ b/Makefile
@@ -339,7 +339,6 @@
 KBUILD_CFLAGS   := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
 		   -fno-strict-aliasing -fno-common \
 		   -Werror-implicit-function-declaration \
-		   -Wno-error=unused-but-set-variable \
 		   -Wno-format-security \
 		   -fno-delete-null-pointer-checks
 KBUILD_AFLAGS   := -D__ASSEMBLY__