drm/i915: Drop redundant dsc_decompression_aux check

If we have no dsc_decompression_aux (only possible on MST)
then we won't have the dsc_dpcd caps either. So checking
both is not needed.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240517145356.26103-2-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>