drm/amd/pm: add some swSMU functions for vangogh.

This patch is to add some swSMU functions for vangogh, to support the
sensor info on "hwmon" and pm info.

Signed-off-by: Xiaojian Du <Xiaojian.Du@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>