This reverts commit fd93f338.

Reason for revert: Out of bounds errors in Unity benchmark (link is internal).

Original change's description:
> [wasm][liftoff] Cache the memory start register
>
> WebAssembly functions often have subsequent memory accesses, and each of
> these memory accesses need the start address of the memory in a register.
> With this CL the register with the memory start address is cached, so
> only the first memory access has to load the memory start address into a
> register, subsequent memory accesses can just reuse the register.
>
> In first measurements with the epic benchmark this reduces the size of
> the generated Liftoff code by a bit more than 5%.
>
> R=​clemensb@chromium.org
>
> Bug: v8:11862
> Change-Id: Ic33e7e3c00a4209570821269c728187affbeadcf
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2947403
> Commit-Queue: Andreas Haas <ahaas@chromium.org>
> Reviewed-by: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#75113}

Bug: v8:11862
Change-Id: I20c7e7d729cf9846499db90c02f8581d7f994ace
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2960216
Auto-Submit: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#75132}