drm/amd/display: Implement new DPCD register handling

[WHY]
There are some monitor timings that seem to be supported without
DSC but actually require DSC to be displayed. A VESA SCR introduced
a new max uncompressed pixel rate cap register that we can use to
handle these edge cases.

[HOW]
SST: Read caps from link and invalidate timings that exceed the
max limit but do not support DSC. Then check for options override
when determining BPP.

MST: Read caps from virtual DPCD peer device or daisy chained SST
monitor and set validation set BPPs to max if pixel rate exceeds
uncompressed limit. Validation set optimization continues as normal.

Reviewed-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Ryan Seto <ryanseto@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>