drm/amd/display: Exit SubVP if MPO in use

drm/amd/display: Exit SubVP if MPO in use

[Description]
Exit SubVP if MPO is in use since SubVP + MPO together is not supported.
- Don't add SubVP at validation time if we see MPO is in use

Issues fixed in the SubVP / MPO transition:
1. Enable phantom pipes in post unlock function to prevent underflow
when an active pipe is being transitioned to be a phantom pipe (VTG
updates take place right away). Also must wait for VUPDATE of the main
pipe to complete first

2. Don't wait for MPCC idle when transitioning a phantom pipe to an
actual pipe. MPCC_STATUS is never asserted due to OTG being off for
phantom pipes

3. When transitioning an active pipe to phantom, program DET right away
(same as disabling the pipe) or the DET update will only take when
the phantom pipe is enabled which can cause DET allocation errors.

4. For K1/K2 programming of phantom pipes, use same settings as the
main pipe. Also don't program K1 / K2 = 0xF ever since the field is only
1 / 2 bits wide.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Solomon Chiu <solomon.chiu@amd.com>
Signed-off-by: Alvin Lee <Alvin.Lee2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>