drm/amd/display: Retain phantom plane/stream if validation fails

drm/amd/display: Retain phantom plane/stream if validation fails

[Description]
- If we fail validation, we should retain the phantom
  stream/planes
- Full updates assume that phantom pipes will be fully
  removed, but if validation fails we keep the phantom
  pipes
- Therefore we have to retain the plane/stream if validation
  fails (since the refcount is decremented before validation,
  and the expectation is that it's fully freed when the  old
  dc_state is released)

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>