Spilling was already fixed if a fixed SIMD register overlaps with an
allocated FP register, but the other way around was missing: If an odd
FP register (in this case d1) is used as a fixed output register, but
this register is in use as the upper half of a SIMD register (in this
case q0), we did not detect this and would just use overwrite the SIMD
half.
This CL also fixes this case.

R=thibaudm@chromium.org

Bug: v8:12330, chromium:1284980
Change-Id: Id3f98b7accd77e38ab4cd5ff8910aaf5ad96a1ed
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3372910Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78514}