drm/i915: Relocate xe AUX hack

Move the xe AUX neutering out from skl_get_plane_caps() into the
caller so that it'll be easier to refactor skl_get_plane_caps()
into a more readable shape. This isn't really hardware specific
anyway, and just some kind of bug/misfeature of xe.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241009182207.22900-9-ville.syrjala@linux.intel.com


Reviewed-by: Jouni Högander <jouni.hogander@intel.com>