net: hns3: add handling of two bits in MAC tunnel interrupts

LINK_UP and LINK_DOWN are two bits of MAC tunnel interrupts, but previous
HNS3 driver didn't handle them. If they were enabled, value of these two
bits will change during link down and link up, which will cause HNS3
driver keep receiving IRQ but can't handle them.

This patch adds handling of these two bits of interrupts, we will record
and clear them as what we do to other MAC tunnel interrupts.

Signed-off-by: Weihang Li <liweihang@hisilicon.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>