drm/amd/pm: enable the fine grain tuning function for vangogh

This patch is to enale the fine grain tuning function for vangogh.

Signed-off-by: Xiaojian Du <Xiaojian.Du@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>