net: hns: Optimize hns_nic_common_poll for better performance

After polling less than buget packages, we need check again. If
there are still some packages, we call napi_schedule add softirq
queue, this is not better way. So we return buget value instead
of napi_schedule.

Signed-off-by: lipeng <lipeng321@huawei.com>
reviewed-by: Yisen Zhuang <yisen.zhuang@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>