drm/amd/display: Add DSC parameters logging to debugfs

[why]
Need to add new parameters to debugfs logging so
we will know what parameters DSC is using for
debug purposes. So we are adding a read function
in debugfs to read DSC status registers

Signed-off-by: Eryk Brol <[email protected]>
Reviewed-by: Mikita Lipski <[email protected]>
Acked-by: Qingqing Zhuo <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: Eryk Brol