This reverts commit 00babf07.

Reason for revert: Broke mac64 https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Mac64/38510/overview

Original change's description:
> [wasm-simd][x64][liftoff] Implement i8x16.popcnt
>
> Extract i8x16.popcnt implementation into a macro-assembler function, and
> reuse it in Liftoff.
>
> Bug: v8:11002
> Change-Id: I86b2f5322c799d44f584cac28c70e0e393bf114f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2676280
> Reviewed-by: Clemens Backes <clemensb@chromium.org>
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Commit-Queue: Zhi An Ng <zhin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#72565}

TBR=gdeepti@chromium.org,clemensb@chromium.org,zhin@chromium.org

Change-Id: I5795b71f65d59237db59907d40c34e4fa7779fe1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:11002
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2682505Reviewed-by: Zhi An Ng <zhin@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72566}