This reverts commit 82d44722.

Reason for revert: we want to keep register allocation general simd binary case

Original change's description:
> [wasm] reduce registers for simd packing in ia32
>
> R=​gdeepti@chromium.org
> BUG=v8:6020
>
> Change-Id: I01644bca95ff5715122c1bc3923024145586a6fd
> Reviewed-on: https://chromium-review.googlesource.com/1112070
> Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
> Commit-Queue: Aseem Garg <aseemgarg@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#53985}

TBR=bbudge@chromium.org,gdeepti@chromium.org,aseemgarg@chromium.org,jing.bao@intel.com

Bug: v8:6020
Change-Id: I878ca82b893fc019e9f769ab2b218fdbaad5f701
Reviewed-on: https://chromium-review.googlesource.com/1114157
Commit-Queue: Aseem Garg <aseemgarg@chromium.org>
Reviewed-by: Aseem Garg <aseemgarg@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54011}