libtuning: Reactivate macbeth locator

Add the missing pieces and store the result inside the image object.
This solution is not very nice, and should be refactored soon. For that
we need a concept to collect temperature and/or image specific results
in a central place. For now it serves the purpose.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

utils/tuning/libtuning/image.py

@@ -24,6 +24,7 @@ class Image:
         self.lsc_only = False
         self.color = -1
         self.lux = -1
+        self.macbeth = None
 
         try:
             self._load_metadata_exif()