android_test_mapping_format: cleanup - "void" funcs don't need explicit ->None.

Fixed import order.

Bug: 196099793
Test: manual

Tested:
$ pylint tools/android_test_mapping_format.py

Change-Id: If3b08adc2a16dde5132aebabf85adf75525c10ef
diff --git a/tools/android_test_mapping_format.py b/tools/android_test_mapping_format.py
index ef1a9b5..ae784cf 100755
--- a/tools/android_test_mapping_format.py
+++ b/tools/android_test_mapping_format.py
@@ -26,8 +26,8 @@
 import json
 import os
 import re
-from typing import Any, Dict
 import sys
+from typing import Any, Dict
 
 _path = os.path.realpath(__file__ + '/../..')
 if sys.path[0] != _path:
@@ -77,7 +77,7 @@
         '\n' if _COMMENTS_RE.match(x) else x for x in json_data.splitlines())
 
 
-def _validate_import(entry: Dict[str, Any], test_mapping_file: str) -> None:
+def _validate_import(entry: Dict[str, Any], test_mapping_file: str):
     """Validates an import setting.
 
     Args:
@@ -141,7 +141,7 @@
                 f'Failed entry: {option}')
 
 
-def process_file(test_mapping_file: str) -> None:
+def process_file(test_mapping_file: str):
     """Validates a TEST_MAPPING file content."""
     try:
         test_mapping_data = json.loads(_filter_comments(test_mapping_file))