PRESUBMIT.cfg: format commits, not files

BUG=None
TEST=CQ passes

Change-Id: Ie6709c6dd0fb44468ff2bea59d3a51aa9abba199
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/eclass-overlay/+/4341812
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Gilberto Contreras <gcontreras@google.com>
Commit-Queue: Gilberto Contreras <gcontreras@google.com>
diff --git a/PRESUBMIT.cfg b/PRESUBMIT.cfg
index 4c723dd..d2adf6b 100644
--- a/PRESUBMIT.cfg
+++ b/PRESUBMIT.cfg
@@ -4,4 +4,4 @@
 
 [Hook Scripts]
 account_checks = profiles/base/accounts/display-accts.py --lint
-cros format = cros format --check ${PRESUBMIT_FILES}
+cros format = cros format --check --commit ${PRESUBMIT_COMMIT} ${PRESUBMIT_FILES}