Fix coreboot project-specific pre-upload hooks

- Coreboot is now a public repo, and is named
  "chromiumos/third_party/coreboot", not "chromeos...".
- Add Signed-off-by presubmit check, since it's a requirement upstream.
- Branch only: Remove BRANCH= check since we're already a branch, and
  remove copyright check because we don't have the file exclusion rules
  setup correctly. Need to investigate how to do that.

BUG=chromium:338878
TEST=Verified that coreboot commit without sign-off was caught by presubmit.
Verified that adding sign-off allowed presubmit pass.

Change-Id: I895bd77fecc91dc0ebacdbac81a563cd736771cf
Original-Change-Id: I6be53109ac278f90004538e5984f8715354ba9f8
Reviewed-on: https://chromium-review.googlesource.com/190685
Reviewed-by: Shawn Nematbakhsh <shawnn@chromium.org>
Commit-Queue: Shawn Nematbakhsh <shawnn@chromium.org>
Tested-by: Shawn Nematbakhsh <shawnn@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
diff --git a/pre-upload.py b/pre-upload.py
index 5320577..ff39b3a 100755
--- a/pre-upload.py
+++ b/pre-upload.py
@@ -640,8 +640,6 @@
     "chromeos/overlays/chromeos-partner-overlay": [_check_manifests],
     "chromeos/platform/ec-private": [_run_checkpatch_ec,
                                      _check_change_has_branch_field],
-    "chromeos/third_party/coreboot": [_check_change_has_branch_field,
-                                      _check_google_copyright],
     "chromeos/third_party/intel-framework": [_check_change_has_branch_field],
     "chromeos/vendor/kernel-exynos-staging": [_run_checkpatch,
                                               _kernel_configcheck],
@@ -653,6 +651,7 @@
                                _check_change_has_branch_field],
     "chromiumos/platform/mosys": [_check_change_has_branch_field],
     "chromiumos/platform/vboot_reference": [_check_change_has_branch_field],
+    "chromiumos/third_party/coreboot": [_check_change_has_signoff_field],
     "chromiumos/third_party/flashrom": [_check_change_has_branch_field],
     "chromiumos/third_party/kernel": [_run_checkpatch, _kernel_configcheck],
     "chromiumos/third_party/kernel-next": [_run_checkpatch,