[wasm-simd][x64] Use kScratchDoubleReg/kScratchReg instead of temp

Drive-by cleanups to merge macro lists which now have the same
instruction selector requirements.

Bug: v8:11384
Change-Id: Id49c43dce897685d5ced19509f390274805739aa
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2716069


Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73075}