drm/xe/xe3p_xpc: Skip compression tuning on platforms without flatccs

drm/xe/xe3p_xpc: Skip compression tuning on platforms without flatccs

The compression overfetch tuning settings only apply to platforms that
support FlatCCS.  In Xe3p_XPC (and any future IPs that also lack
compression) some of the registers being adjusted by this tuning will
not exist or may have been repurposed for something else, so we should
take care not to try to program them.

Note that our xe_rtp_match_has_flatccs() function will also return false
on platforms that do have FlatCCS in the hardware design, but have
compression manually disabled in the BIOS.  On such platforms the
registers still exist (and it would be fine to continue programming
them), but they would have no effect, so skipping that tuning is also
safe.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Shekhar Chauhan <shekhar.chauhan@intel.com>
Link: https://lore.kernel.org/r/20251016-xe3p-v3-22-3dd173a3097a@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>