[compiler] Simplify "==0" branches in MachineOperatorReducer

Bug: v8:12484
Change-Id: I0667c7464c0dd71338bc199a24a69248a7a0a525
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3497303


Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Owners-Override: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Darius Mercadier <dmercadier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79379}