drm/amdgpu: enable more pm sysfs under SRIOV 1-VF mode

Enable pp_num_states, pp_cur_state, pp_force_state, pp_table sysfs under
SRIOV 1-VF scenario.

Signed-off-by: Jiawei Gu <Jiawei.Gu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>