Add cos_license_check hook to src/overlays

We currently only have cos_ebuild_license_header_check in
src/overlays, but we should also check non-ebuild files as well.

BUG=b/149121748
TEST=repo upload . --dry-run
RELEASE_NOTE=None

Change-Id: Ifc60185858c15d53dd18f751da50ff884837f775
Reviewed-on: https://cos-review.googlesource.com/c/cos/overlays/board-overlays/+/9360
Reviewed-by: Roy Yang <royyang@google.com>
Tested-by: Dexter Rivera <riverade@google.com>
diff --git a/PRESUBMIT.cfg b/PRESUBMIT.cfg
index 1038191..1f1de67 100644
--- a/PRESUBMIT.cfg
+++ b/PRESUBMIT.cfg
@@ -11,6 +11,7 @@
 # On by default, but required for options below.
 cros_license_check: false
 cos_ebuild_license_header_check: true
+cos_license_check: true
 
 [Hook Overrides Options]
 # Ignore generated chromeos-config C files.