drm/amd/display: SubVP high refresh only if all displays >= 120hz

[Description]
- SubVP high refresh should only be enabled if all displays
  are >= 120hz. We do not want to accidentally enables configs
  such as 60hz[SubVP] + 120hz[SubVP]
- Ensure that the SubVP config generation code does not produce
  configs such as 60hz[SubVP] + 120hz[SubVP]
- Also add admissibility checks to ensure these configs do not
  pass as valid configs

Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Alvin Lee <alvin.lee2@amd.com>
Reviewed-by: Dillon Varone <Dillon.Varone@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>