binman: Add a function to obtain the image for an Entry

At present we have an 'image' property in the entry for this purpose, but
this is not necessary and seems error-prone in the presence of
inheritance. Add a function instead. The Entry_section class overrides
this with a special version, since top-level sections are in fact images,
since Image inherits Entry_section.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/binman/entry.py

@@ -700,3 +700,11 @@ features to produce new behaviours.
         data = self.ReadData(decomp)
         self.ProcessContentsUpdate(data)
         self.Detail('Loaded data size %x' % len(data))
+
+    def GetImage(self):
+        """Get the image containing this entry
+
+        Returns:
+            Image object containing this entry
+        """
+        return self.section.GetImage()