Partially revert "drm/amd/display: update add plane to context logic with a new algorithm"

This partially reverts commit 460ea898 ("drm/amd/display: update add
plane to context logic with a new algorithm").

The new secondary pipe allocation logic triggers an issue with a
specific hardware state transition and causes a frame of corruption when
toggling between windowed MPO and ODM desktop only mode. Ideally hwss is
supposed to handle this scenario. We are temporarily reverting the logic
and investigate the root cause why this transition would cause
corruptions.

Fixes: 460ea898

 ("drm/amd/display: update add plane to context logic with a new algorithm")
Reviewed-by: Martin Leung <martin.leung@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>