binman: Support adding files

In some cases it is useful to add a group of files to the image and be
able to access them at run-time. Of course it is possible to generate
the binman config file with a set of blobs each with a filename. But for
convenience, add an entry type which can do this.

Add required support (for adding nodes and string properties) into the
state module.

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

tools/binman/entry.py

@@ -179,6 +179,9 @@ class Entry(object):
             return Set([fname])
         return Set()
 
+    def ExpandEntries(self):
+        pass
+
     def AddMissingProperties(self):
         """Add new properties to the device tree as needed for this entry"""
         for prop in ['offset', 'size', 'image-pos']: