drm/i915/xehp: Drop aux table invalidation on FlatCCS platforms

Platforms with FlatCCS do not use auxiliary planes for compression
control data and thus do not need traditional aux table invalidation
(and the registers no longer even exist).

Original-author: CQ Tang
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220301052952.1706597-1-matthew.d.roper@intel.com