drm/amd/powerplay: add function display_configuration_changed for navi10

1.add callback function to support navi10 asic.
2.Remove unnecessary logical code.

Signed-off-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>