drm/i915: Clean up the LPE audio platform data

drm/i915: Clean up the LPE audio platform data

Split the LPE audio platform data into a port specific
chunk and device specific chunk. Eventually we'll have
a port specific chunk for each port, but for now we'll
stick to just one.

We'll also get rid of the intel_hdmi_lpe_audio_eld structure
which doesn't seem to have any real reason to exist.

v2: Organize per port instead of per pipe

Cc: Takashi Iwai <tiwai@suse.de>
Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170427160231.13337-9-ville.syrjala@linux.intel.com
Reviewed-by: Takashi Iwai <tiwai@suse.de>