drm/amd/display: take ODM slice count into account when deciding DSC slice

[why]
DSC slice must be divisible by ODM slice count.

[how]
If DSC slice count is not a multiple of ODM slice count, increase DSC
slice until it is. Otherwise fail to compute DSC configuration.

Reviewed-by: Chaitanya Dhere <chaitanya.dhere@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>