patman: Support the 'reverse' option for 'git log'

This option is currently not supported, but needs to be, for buildman to
operate as expected.

Reported-by: York Sun <yorksun@freescale.com>
Signed-off-by: Simon Glass <sjg@chromium.org>

tools/patman/gitutil.py

@@ -38,6 +38,8 @@ def LogCmd(commit_range, git_dir=None, oneline=False, reverse=False,
         cmd.append('--oneline')
     if use_no_decorate:
         cmd.append('--no-decorate')
+    if reverse:
+        cmd.append('--reverse')
     if count is not None:
         cmd.append('-n%d' % count)
     if commit_range: