This reverts commit df204288.

Reason for revert: Broke noavx https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20-%20debug/31698

Original change's description:
> [wasm-simd][x64] Cleanup unnecessary CpuFeatureScope
> 
> There are a couple more left in some i64x2 ops, but those are not in the
> proposal, so I've left them as it is.
> 
> Bug: v8:9561
> Change-Id: I3f6a4113c8054229eb6532d83ff16174a3208418
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2128849
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Commit-Queue: Zhi An Ng <zhin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#66990}

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

Change-Id: Ib42dbf70ab8ee97ed1d2f809ea305c22213ae960
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9561
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2134653Reviewed-by: Zhi An Ng <zhin@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66999}