presubmit: enable checkpatch checks

We're moving the hardcoded check lists out of the pre-upload script.

BUG=chromium:466264
TEST=uploading a CL w/out a branch line is rejected

Change-Id: I612c5b8d7c912efc0337a2fcf9dbb0bf5d57a17d
Signed-off-by: Mike Frysinger <vapier@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/262622
Reviewed-by: Randall Spangler <rspangler@chromium.org>
diff --git a/PRESUBMIT.cfg b/PRESUBMIT.cfg
index ddaa7ff..568d484 100644
--- a/PRESUBMIT.cfg
+++ b/PRESUBMIT.cfg
@@ -1,4 +1,5 @@
 [Hook Overrides]
+checkpatch_check: true
 
 # We need to manually ensure that any new file added has the correct header.
 # There are too many existing files that we are not going to be changing the