Fix NPE if the camera cannot be connected.

bug:5673972
Change-Id: I85587bd982e0af5dd7c3630958e105571d8e12d9
diff --git a/src/com/android/camera/Camera.java b/src/com/android/camera/Camera.java
index 90621c8..a391e20 100644
--- a/src/com/android/camera/Camera.java
+++ b/src/com/android/camera/Camera.java
@@ -1578,7 +1578,7 @@
         stopPreview();
         // Close the camera now because other activities may need to use it.
         closeCamera();
-        mCameraSound.release();
+        if (mCameraSound != null) mCameraSound.release();
         resetScreenOn();
 
         // Clear UI.