drm/amd/display: fixed an error related to 4:2:0/4:2:2 DSC

[Why]
OPTC_BYTES_PER_PIXEL calculation for 4:2:2 and 4:2:0 could have error.

[How]
Change to use following formula:
OPTC_DSC_BYTES_PER_PIXEL = ceiling((chunk size * 2^28) / slice width)

v2: squash in 64 bit divide fix (Alex)

Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Bing Guo <Bing.Guo@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>