Removed unused-but-set variable check from Makefile

This causes issues compiling with more up-to-date compilers
if not disabled (the current version of the kernel has tons
of these).

Change-Id: I3d833921c28959639ac36926ccc0edf49c308228
diff --git a/Makefile b/Makefile
index 2c287e1..aa2f10633 100755
--- a/Makefile
+++ b/Makefile
@@ -339,6 +339,7 @@
 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__