When the transcoder:port mapping on Haswell HDMI/DP audio is changed
during the stream playback, the sound gets lost.  Typically this
problem is seen when the user switches the graphics mode from eDP+DP
to DP-only configuration, where CRTC 1 is used for DP in the former
while CRTC 0 is used for the latter.

The graphics controller notifies the change via the normal ELD update
procedure, so we get the intrinsic event.  For enabling the sound
again, the HDMI audio driver needs to reset the pin and set up the
audio infoframe again.

This patch achieves it by:
- keep the current status of channels and info frame setup in per_pin
  struct,
- check the reconnection in the intrinsic event handler,
- reset the pin and the re-invoke hdmi_setup_audio_infoframe()
  accordingly.

The hdmi_setup_audio_infoframe() function has been changed, too, so
that it can be invoked without passing the substream instance.

The patch is mostly based on the work by Mengdong Lin.

Cc: Mengdong Lin <mengdong.lin@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>