binman: Change how faked blobs are created

At present fake blobs are created but internally an empty blob is used.
Change it to use the contents of the faked file. Also return whether the
blob was faked, in case the caller needs to know that.

Add a TODO to put fake blobs in their own directory.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>

tools/binman/entry.py

@@ -999,15 +999,18 @@ features to produce new behaviours.
             fname (str): Filename to check
 
         Returns:
-            fname (str): Filename of faked file
+            tuple:
+                fname (str): Filename of faked file
+                bool: True if the blob was faked, False if not
         """
         if self.allow_fake and not pathlib.Path(fname).is_file():
             outfname = tools.get_output_filename(os.path.basename(fname))
             with open(outfname, "wb") as out:
                 out.truncate(1024)
             self.faked = True
-            return outfname
-        return fname
+            tout.info(f"Entry '{self._node.path}': Faked file '{outfname}'")
+            return outfname, True
+        return fname, False
 
     def CheckFakedBlobs(self, faked_blobs_list):
         """Check if any entries in this section have faked external blobs