Cleanup Memcpy and use get/set_simd_register_by_lane

Change-Id: Icbdd838e075d93d75064bd8e47eb95c02f1da9d4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2568589
Commit-Queue: Junliang Yan <junyan@redhat.com>
Reviewed-by: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#71577}