drm/amd/display: Add DPIA Link Encoder Assignment Fix for DCN35

For DPIA we should have preferred DIG assignment based on DPIA selected
as per the ASIC design

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: George Shen <george.shen@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Mustapha Ghaddar <mghaddar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>