drm/amd/display: fix high part address in dm_plane_helper_prepare_fb()

drm/amd/display: fix high part address in dm_plane_helper_prepare_fb()

The high part calculation of luma and chroma address' was
missing in dm_plane_helper_prepare_fb().

This fix brings uniformity in the address' at atomic_check
and atomic_commit for both RGB & YUV planes.

Signed-off-by: Shirish S <[email protected]>
Reviewed-by: Michel Dänzer <[email protected]>
Reviewed-by: Alex Deucher <[email protected]>
Reviewed-by: Harry Wentland <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>