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 <shirish.s@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>