u_boot_pylib: Move gitutil into the library

Move this file into U-Boot's Python library, so that it is no-longer
part of patman.

This makes a start on:

https://source.denx.de/u-boot/custodians/u-boot-dm/-/issues/35

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/u_boot_pylib/__init__.py b/tools/u_boot_pylib/__init__.py
index 63c88e8..807a62e 100644
--- a/tools/u_boot_pylib/__init__.py
+++ b/tools/u_boot_pylib/__init__.py
@@ -1,4 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0+
 
-__all__ = ['command', 'cros_subprocess','terminal', 'test_util', 'tools',
-	   'tout']
+__all__ = ['command', 'cros_subprocess', 'gitutil', 'terminal', 'test_util',
+           'tools', 'tout']