Remember to tear down ASEC bind mount.

Bug: 19993667
Change-Id: I17093f0f9abe8762e5ee4f38ce99f9024e419dfc
diff --git a/PublicVolume.cpp b/PublicVolume.cpp
index 9a68f50..dc746cf 100644
--- a/PublicVolume.cpp
+++ b/PublicVolume.cpp
@@ -177,6 +177,7 @@
         mFusePid = 0;
     }
 
+    ForceUnmount(kAsecPath);
     ForceUnmount(mFusePath);
     ForceUnmount(mRawPath);