Add some explicit error log messages

Change-Id: I8a69157b75a67f0d3c19f05775a8cb0629232299
diff --git a/media/libstagefright/CameraSource.cpp b/media/libstagefright/CameraSource.cpp
index 3e31d61..89cb135 100644
--- a/media/libstagefright/CameraSource.cpp
+++ b/media/libstagefright/CameraSource.cpp
@@ -93,6 +93,9 @@
        return OMX_COLOR_Format16bitRGB565;
     }
 
+    LOGE("Uknown color format (%s), please add it to "
+         "CameraSource::getColorFormat", colorFormat);
+
     CHECK_EQ(0, "Unknown color format");
 }