Similar to the case of fixed registers, we need to consider both cases:
A SIMD register might collide with either the low or high FP register,
or the FP register might collide with a previously allocated SIMD
register. We did only consider the first case so far.

R=thibaudm@chromium.org

Bug: chromium:1286253, v8:12330
Change-Id: Id4c995586cc8b97a2e131ee9d3417525e409bcef
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3380597Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78633}