[Intel-gfx] DP audio API changes for identifying displays connected to a port

[Dhinakaran Pandiyan]

An additional parameter has been added to the API's between i915 and audio
drivers to identify display devices that can be connected to the same port.
Currently only the port identity is being shared, but this is not
sufficient as multiple displays can be driven from the same port
(E.g. DP MST). This patch makes the API changes with dummy changes in the
audio driver (Thanks Libin). Implementation to fully enable DP MST audio
will follow later.

Dhinakaran Pandiyan(1):
drm/i915/dp: DP audio API changes for MST