ppc64: [baseline] Implement ToRegister

Drive-by: fix compilation error
Change-Id: I418cd6d6aaff4bf21c86db39a300bc41240c27d6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3542987


Reviewed-by: Milad Farazmand <mfarazma@redhat.com>
Commit-Queue: Junliang Yan <junyan@redhat.com>
Cr-Commit-Position: refs/heads/main@{#79559}