net: hns3: fix napi_disable not return problem

While doing DOWN, the calling of napi_disable() may not return, since the
napi_complete() in the hns3_nic_common_poll() will never be called when
HNS3_NIC_STATE_DOWN is set. So we need to call napi_complete() before
checking HNS3_NIC_STETE_DOWN.

Fixes: ff0699e0 ("net: hns3: stop napi polling when HNS3_NIC_STATE_DOWN is 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>