binman: Allow faked blobs in blob-ext-list

Since this is a list of blobs, each blob should have the ability to be
faked, as with blob-ext. Update the Entry base class to set allow_fake
and use the base class in the section code also, so that this propagagtes
to blob-ext-list, which is not a section.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index 6a76473..ac6aabb 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -4982,6 +4982,14 @@
             err,
             "Image '.*' has faked external blobs and is non-functional: .*")
 
+    def testExtblobListFaked(self):
+        """Test an extblob with missing external blob that are faked"""
+        with test_util.capture_sys_output() as (stdout, stderr):
+            self._DoTestFile('216_blob_ext_list_missing.dts',
+                             allow_fake_blobs=True)
+        err = stderr.getvalue()
+        self.assertRegex(err, "Image 'main-section'.*faked.*: blob-ext-list")
+
 
 if __name__ == "__main__":
     unittest.main()