drm/amd/display: update blank state on ODM changes

When we are dynamically adding new ODM slices, we didn't update
blank state, if the pipe used by new ODM slice is previously blanked,
we will continue outputting blank pixel data on that slice causing
right half of the screen showing blank image.

The previous fix was a temporary hack to directly update current state
when committing new state. This could potentially cause hw and sw
state synchronization issues and it is not permitted by dc commit
design.

Cc: stable@vger.kernel.org
Fixes: 7fbf451e ("drm/amd/display: Reinit DPG when exiting dynamic ODM")
Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>