drm/amdgpu/powerplay: actually return the power with the new query

Set query to the power value so we actually return it.  Fixes
no power value returned on asics with the new query.

Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>
Reviewed-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>