drm/amd/display: Unify blank_phantom and blank_pixel_data

[Why]
dcn32_blank_phantom() does not consider the subVP+ODM case when blanking.
Only one of the pipes will get blanked. Remaining pipes are not blanked.
Will cause underflow in the phantom pipe when enabling the CRTC.

[How]
Use blank_pixel_data() instead of blank_phantom().
remove dcn32_blank_phantom() since logic is identical.
Different DPG dimensions get programmed when blanking phantom pipes.
Previously had phantom pipes use DPG dimensions of the main stream.
Now use DPG dimensions of the phantom streams

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Austin Zheng <Austin.Zheng@amd.com>
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>