drm/amdgpu/sriov: reopen sienna_child smu ip block under sriov

open smu ip block meets with one-vf mode need

Signed-off-by: Jane Jian <Jane.Jian@amd.com>
Reviewed-by: Monk Liu <monk.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>