Set the default lun file to one that is more likely to be correct

Change-Id: I23ceb2f33f62be32dcaec26cf67b1604de0b3152
diff --git a/variables.h b/variables.h
index d840b8d..4b80ee3 100755
--- a/variables.h
+++ b/variables.h
@@ -174,7 +174,7 @@
 //#define MAX_ARCHIVE_SIZE 52428800LLU // 50MB split for testing
 
 #ifndef CUSTOM_LUN_FILE
-#define CUSTOM_LUN_FILE "/sys/class/android_usb/android0/f_mass_storage/lun%d/file"
+#define CUSTOM_LUN_FILE "/config/usb_gadget/g1/functions/mass_storage.0/lun.%d/file"
 #endif
 
 #define SCRIPT_FILE_TMP "/tmp/openrecoveryscript"