drm/amd/powerplay: move the funciton of conv_profile_to_workload to asic file

the function of conv_profile_to_workload is asic related function,
so move them 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>