camera2: Implement ICameraDeviceUser::waitUntilIdle

Also fixed some logging typo

Change-Id: Ib254bdb137dca10b12595c23aeb1c53097423425
diff --git a/include/camera/photography/ICameraDeviceUser.h b/include/camera/photography/ICameraDeviceUser.h
index 3ea49f4..45988d0 100644
--- a/include/camera/photography/ICameraDeviceUser.h
+++ b/include/camera/photography/ICameraDeviceUser.h
@@ -61,6 +61,8 @@
     virtual status_t        getCameraInfo(/*out*/
                                           CameraMetadata* info) = 0;
 
+    // Wait until all the submitted requests have finished processing
+    virtual status_t        waitUntilIdle() =  0;
 };
 
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