drm/i915: Split g4x+ DP audio presence detect from port enable

drm/i915: Split g4x+ DP audio presence detect from port enable

Follow the hsw+ approach toggle the audio presence detect
when we set up the ELD, instead of doing it when turning the
port on/off.

This will facilitate audio enable/disable to happen during
fastsets instead of requiring a full modeset.

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231121054324.9988-7-ville.syrjala@linux.intel.com