llvm_tools: `rev-parse` in the right repo

BUG=b:335901793
TEST=Ran the script with --dry-run

Change-Id: Ifadfa47e5ace65b9fef61ebbad00c6e3c5683a68
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/5472463
Tested-by: George Burgess <gbiv@chromium.org>
Reviewed-by: Bob Haarman <inglorion@chromium.org>
Commit-Queue: George Burgess <gbiv@chromium.org>
1 file changed