Removing prefetch operations as per the vote in the github issue:
https://github.com/WebAssembly/simd/pull/352

Bug:v8:11168

Change-Id: Ia72684e68ce886f8f26a7d3b5bea601be416dfab
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2771758Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Zhi An Ng <zhin@chromium.org>
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73578}