patman: force git log commands to not use color

Colored logs confuse patman when analyzing logs.
Add --no-color option in git log commands in case
the default config has color.

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/tools/patman/patchstream.py b/tools/patman/patchstream.py
index 0503bac..ad280cc 100644
--- a/tools/patman/patchstream.py
+++ b/tools/patman/patchstream.py
@@ -344,7 +344,8 @@
         start: Commit to start from: 0=HEAD, 1=next one, etc.
         count: Number of commits to list
     """
-    pipe = [['git', 'log', '--reverse', 'HEAD~%d' % start, '-n%d' % count]]
+    pipe = [['git', 'log', '--no-color', '--reverse', 'HEAD~%d' % start,
+	'-n%d' % count]]
     stdout = command.RunPipe(pipe, capture=True)
     series = Series()
     ps = PatchStream(series, is_log=True)