After https://crrev.com/c/2695401, CachRegs needed to be defined
on PPC to overwrite the default value "0xff".

The default value was causing the following failure on some tests:

```
#
# Fatal error in ../../src/wasm/baseline/liftoff-register.h, line 160
# Debug check failed: 0 != kLiftoffAssemblerGpCacheRegs & reg.bit()
  (0 vs. 0).
```

Values are taken from `src/execution/ppc/frame-constants-ppc.h`.

Change-Id: Idfc1d0fdc20d0b5aabc25e5b5809a93073a2dc3d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2698930Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#72827}