patman: Use --no-pager' to stop git from forking a pager

In a headless environment the pager can apparently hang. We don't want a
pager anyway so let's request that none be used.

Reported-by: Tom Rini <trini@ti.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/gitutil.py b/tools/patman/gitutil.py
index 45276e6..fbd170f 100644
--- a/tools/patman/gitutil.py
+++ b/tools/patman/gitutil.py
@@ -33,7 +33,7 @@
     cmd = ['git']
     if git_dir:
         cmd += ['--git-dir', git_dir]
-    cmd += ['log', '--no-color']
+    cmd += ['--no-pager', 'log', '--no-color']
     if oneline:
         cmd.append('--oneline')
     if use_no_decorate: