drm/amd/display: Fix incorrect DSC recompute trigger

A stream without dsc_aux should not be eliminated from
the dsc determination. Whether it needs a dsc recompute depends on
whether its mode has changed or not. Eliminating such a no-dsc stream
from the dsc determination policy will end up with inconsistencies
in the new dc_state when compared to the current dc_state,
triggering a dsc recompute that should not have happened.

Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>