When VF NIC client's init_instance() succeeds, it means this client
has been registered successfully, so we use HCLGEVF_STATE_NIC_REGISTERED
to indicate that. And before calling VF NIC client's uninit_instance(),
we clear this state.

So any operation of VF NIC client from HCLGEVF is not allowed if this
state is not set.
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>