Fix misc-macro-parentheses warnings.

Bug: 28705665
Change-Id: I1ad468741c6f117817099d2ba87374dce2b776a9
diff --git a/drm/common/ReadWriteUtils.cpp b/drm/common/ReadWriteUtils.cpp
index d696f16..16b5b34 100644
--- a/drm/common/ReadWriteUtils.cpp
+++ b/drm/common/ReadWriteUtils.cpp
@@ -30,7 +30,7 @@
 
 using namespace android;
 
-#define FAILURE -1
+#define FAILURE (-1)
 
 String8 ReadWriteUtils::readBytes(const String8& filePath) {
     FILE* file = NULL;