Fix vold cannot create obb directory

Test: setupAppDir works now
Change-Id: I4bc67ecb57c30b1d0728580abc738e91f97de722
diff --git a/Utils.cpp b/Utils.cpp
index 6a67071..84bed34 100644
--- a/Utils.cpp
+++ b/Utils.cpp
@@ -255,7 +255,7 @@
         if (!IsFilesystemSupported("sdcardfs")) {
             gid = AID_MEDIA_RW;
         }
-    } else if (StartsWith(pathFromRoot, kAppMediaDir)) {
+    } else if (StartsWith(pathFromRoot, kAppObbDir)) {
         appDir = kAppObbDir;
         if (!IsFilesystemSupported("sdcardfs")) {
             gid = AID_EXT_OBB_RW;