drm/amd/display: Filter out AC mode frequencies on DC mode systems

drm/amd/display: Filter out AC mode frequencies on DC mode systems

Why:
Limit maximum clock speeds to DC mode limits for DC mode systems
How:
Store DC mode limits when individual clocks are initialized and
cap the values when building the clock table

Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Austin Zheng <austin.zheng@amd.com>
Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>