pre-upload: remove unused input for clang-format

It looks like the line is copied from _run_checkpatch() below, but
clang-format.py does not expect any content from stdin.

BUG=None
TEST=Add a bad-formatted line and check pre-upload.py can still catch
     it.

Change-Id: I8e1c3107ae81fdd8de50d54d9707ab43590f9f53
Reviewed-on: https://chromium-review.googlesource.com/1517252
Commit-Ready: Shik Chen <shik@chromium.org>
Tested-by: Shik Chen <shik@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/pre-upload.py b/pre-upload.py
index e9b1f06..32ccd8d 100755
--- a/pre-upload.py
+++ b/pre-upload.py
@@ -1260,7 +1260,6 @@
   cmd = [os.path.join(hooks_dir, 'clang-format.py')] + options
   cmd_result = cros_build_lib.RunCommand(cmd=cmd,
                                          print_cmd=False,
-                                         input=_get_patch(commit),
                                          stdout_to_pipe=True,
                                          combine_stdout_stderr=True,
                                          error_code_ok=True)