drm/amd/powerplay: move the function of get[set]_power_profile to asic file

The callback of get[set]_power_profile is asic related function,
so move theme into vega20_ppt file.

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>