dtoc: Ignore unwanted files when scanning for drivers

We should ignore anything in the .git directory or any of the
build-sandbox, etc. directories created by 'make check'. These can confuse
dtoc. Update the code to ignore these.

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

tools/dtoc/src_scan.py

@@ -345,6 +345,11 @@ class Scanner:
         This procedure will populate self._drivers and self._driver_aliases
         """
         for (dirpath, _, filenames) in os.walk(self._basedir):
+            rel_path = dirpath[len(self._basedir):]
+            if rel_path.startswith('/'):
+                rel_path = rel_path[1:]
+            if rel_path.startswith('build') or rel_path.startswith('.git'):
+                continue
             for fname in filenames:
                 if not fname.endswith('.c'):
                     continue