drm/amdgpu/sriov: Need to clear kiq position

As will clear vf fw during unload driver, to avoid idle fail. Need
to clear KIQ portion also.

Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Ack-by: Monk.liu <monk.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>