net: hns3: Make hclgevf_update_link_mode static

Fix sparse warning:

drivers/net/ethernet/hisilicon/hns3/hns3vf/hclgevf_main.c:407:6:
 warning: symbol 'hclgevf_update_link_mode' was not declared. Should it be static?

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>