checkpatch.pl: Update to latest from v4.17

Copied checkpatch and related files from the v4.17 kernel.org
repository.

BUG=chromium:850856
TEST=repo upload and check warnings
Signed-off-by: Kuo-Hsin Yang <vovoy@chromium.org>

Change-Id: Ib3451fdb161d61cbf151742f9bf7900cd3023811
Reviewed-on: https://chromium-review.googlesource.com/1092557
Commit-Ready: Vovo Yang <vovoy@chromium.org>
Tested-by: Vovo Yang <vovoy@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
2 files changed