drm/edid: convert drm_detect_monitor_audio() to use cea db iter

Iterate through all CEA data blocks.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/a7f0c380da9526f8dd6f758d7a748bca7b4da6ce.1651569697.git.jani.nikula@intel.com