drm/i915/audio: Hardware ELD readout

Read out the ELD from the hardware buffer, or from our stashed
copy for the audio component, so that we can hook up the state
checker to validate it.

v2: Deal with the platforms using acomp

Cc: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Cc: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Jani Nikula <jani.nikula@intel.com> #v1
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230124144628.4649-7-ville.syrjala@linux.intel.com