drm/amd/display: DSC Clock enable debugfs write entry

[Why]
Need a mechanism to force enable DSC on any connector

[How]
Debugfs entry overwrites newly added connector's dsc preffered
settings structure and sets dsc_clock_en flag on it.
During the attomic commit, depending if connector is SST or
MST, we will enable DSC manually by overwriting stream's DSC flag.

Signed-off-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
Reviewed-by: Mikita Lipski <Mikita.Lipski@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>