drm/amd/display: Use forced DSC bpp in DML

[Why]
DSC config is calculated separately from DML calculations.
DML should use these separately calculated DSC params. The issue is
that the calculated bpp is not properly propagated into DML.

[How]
Correctly used forced_bpp value in DML.

Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: George Shen <george.shen@amd.com>
Tested-by: Mark Broadworth <mark.broadworth@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>