drm/amd/display: Add minimal pipe split transition state

[WHY?]
When adding/removing a plane to some configurations, unsupported pipe
programming can occur when moving to a new plane.  Such cases include pipe
split on multi-display, with MPO, and/or ODM.

[HOW?]
Add a safe transistion state that minimizes pipe usage before programming
new configuration. When adding a plane, the current state has the least
pipes required so it is applied without splitting.  This must be applied
prior to updating the plane_state for seamless transition.  When removing a
plane, the new state has the least pieps required so it is applied without
splitting.

Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>