Vold: remove unused define

Introduced in commit 36801cccf27152c9eca5aab6ba3527221525110f,
but never used.

Test: m
Bug: 31338270
Change-Id: I90bbab0208032b75b3700b02f0dc053b0e5ed38a
diff --git a/VolumeBase.cpp b/VolumeBase.cpp
index 627feba..3f27d87 100644
--- a/VolumeBase.cpp
+++ b/VolumeBase.cpp
@@ -30,8 +30,6 @@
 
 using android::base::StringPrintf;
 
-#define DEBUG 1
-
 namespace android {
 namespace vold {