drm/amd/display: Enable SubVP on 1080p60 displays

drm/amd/display: Enable SubVP on 1080p60 displays

[Description]
- Previously SubVP would never be selected on 1080p60 displays because
  it has too much vactive margin. However, implement a change to allow
  it like how 1440p60 is allowed.
- Add a new struct such that we have a list of allowed modes for
  enabling subvp with vactive margin (currently 1080p60 and 1440p60)
- Also ensure to block drr + vblank cases to prevent unexpected
  enablement of new display configs
- Update SW cursor fallback for these new potential cases as well

Reviewed-by: Samson Tam <samson.tam@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>