drm/i915/dp: Populate DSC PPS SDP and send PPS infoframes

DSC PPS secondary data packet infoframes are filled with
DSC picure parameter set metadata according to the DSC standard.
These infoframes are sent to the sink device and used during DSC
decoding.

v3:
* Rename to intel_dp_write_pps_sdp (Ville)
* Use const intel_crtc_state (Ville)
v2:
* Rebase ond drm-tip

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181128202628.20238-10-manasi.d.navare@intel.com