misc/mei/hdcp: Fill transcoder index in port info

For gen12+ platform we need to pass the transcoder info
as part of the port info into ME FW.

This change fills the payload for ME FW from hdcp_port_data.

v2:
  Doc is enhanced for physical_port and attached_transcoder [Tomas]

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Shashank Sharma <shashank.sharma@intel.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190828164216.405-5-ramalingam.c@intel.com