drm/amd/display: add hdmi2.1 dsc pps packet programming

This change adds EMP packet programming for enabling dsc with
hdmi. The packets are structured according to VESA HDMI 2.1x
r2 spec, section 10.10.2.2.

Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>