drm/amd/display: Enable dc mode clock switching for DCN32x

- DC mode clock switch interface was previously only executed
  for DCN303. Enable it for DCN32x so that the interface is called
  correctly
- Assign function pointers for DCN32x that are used in the dc mode
  interface
- Update the dc mode interface to work generically for each ASIC
- In update_clocks, make sure to consider softmax if we're in DC mode

Reviewed-by: Jun Lei <jun.lei@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>