We can avoid the scratch register by directly using the operand in the
"sub" instruction.

R=victorgomes@chromium.org

Bug: v8:12017
Change-Id: Ib1768a92b0ef98bf7dbed522f467eff395d08e8d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3069138Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76082}