binman: Fix comment in bsection.GetEntries()

This comment is out of date as it does not correctly describe the return
value. Fix it.

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

tools/binman/bsection.py

@@ -399,10 +399,10 @@ class Section(object):
             raise ValueError("%s: No such property '%s'" % (msg, prop_name))
 
     def GetEntries(self):
-        """Get the number of entries in a section
+        """Get the dict of entries in a section
 
         Returns:
-            Number of entries in a section
+            OrderedDict of entries in a section
         """
         return self._entries