net: hns: Clean rx fbd when ae stopped.

[ Upstream commit 31f6b61d810654fb3ef43f4d8afda0f44b142fad ]

If there are packets in hardware when changing the speed or duplex,
it may cause hardware hang up.

This patch adds the code to wait rx fbd clean up when ae stopped.

Signed-off-by: Yonglong Liu <liuyonglong@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>