drm/amd/display: redesign dce/dcn clock voltage update request

The goal of this change is to move clock programming and voltage
requests to a single function. As of this change only dce is affected.

Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>