dtoc: Move test files into a test/ directory

It is confusing to have the test files in the same places as the
implementation. Move them into a separate directory.

Add a helper function for test_dtoc, to avoid repeating the same
path.

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

tools/dtoc/test_src_scan.py

@@ -59,7 +59,8 @@ class TestSrcScan(unittest.TestCase):
     def test_additional(self):
         """Test with additional drivers to scan"""
         scan = src_scan.Scanner(
-            None, True, [None, '', 'tools/dtoc/dtoc_test_scan_drivers.cxx'])
+            None, True,
+            [None, '', 'tools/dtoc/test/dtoc_test_scan_drivers.cxx'])
         scan.scan_drivers()
         self.assertIn('sandbox_gpio_alias2', scan._driver_aliases)
         self.assertEqual('sandbox_gpio',