we need register pm sysfs for virt in order
to support dpm level modification because
smu ip block will not be added under SRIOV

v2: whitespace fixes (Alex)
Signed-off-by: Yintian Tao <yttao@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>