ASoC: hdac_hdmi: Begin to add support for DP Multi-stream audio

With MST each pin contains several ports to which device can be
connected.

As a preparatory work to support DP MST this patch adds below changes:
1. Defines the port structure and moves all stream related information
   like ELD, converter list, chmap to port.
2. Creates ports for each pin based on the max_ports support.
3. Based on Pin-Port combination creates DAPM Mux widget instead of Pin
   to allow user to select a converter.
4. Port zero is the default port when pin does not support MST.
Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>