vold2: Wire up more of the mount function

Signed-off-by: San Mehat <san@android.com>
diff --git a/DirectVolume.cpp b/DirectVolume.cpp
index 0817624..515a33a 100644
--- a/DirectVolume.cpp
+++ b/DirectVolume.cpp
@@ -119,3 +119,8 @@
 
 void DirectVolume::handlePartitionRemoved(const char *devpath, NetlinkEvent *evt) {
 }
+
+int DirectVolume::prepareToMount(int *major, int *minor) {
+    errno = ENOSYS;
+    return -1;
+}