drm/i915/xe2lpd: Don't try to program PLANE_AUX_DIST

drm/i915/xe2lpd: Don't try to program PLANE_AUX_DIST

Since Xe2LPD technically has FlatCCS, it doesn't have AuxCCS registers
like PLANE_AUX_DIST.  However we currently have HAS_FLAT_CCS hardcoded
to 0 since compression isn't ready; we need to make sure this doesn't
cause the display code to go back to trying to write this register.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230919192128.2045154-8-lucas.demarchi@intel.com