drm/amd/display: Only commit SubVP state after pipe programming

[Description]
We only want to commit the SubVP config to DMCUB
after the main and phantom pipe programming has
completed. Commiting the state early can cause
issues such as P-State being allowed by the HW
early which causes the SubVP state machine to
go into a bad state

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Brian Chang <Brian.Chang@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>