net: hns3: Clear TX/RX rings when stopping port & un-initializing client

When we down the port, some packets are left in TX/RX buffer. When we
up the port again, these old packets are forwarded to protocol stack
or are sent to internet. It will make some problem. TX/RX buffer should
be cleared when stopping port. This patch adds some function to ensure
the buffer is clean when port is started. We should clear the rings
when clients are being un-initialized as well.

Fixes: 76ad4f0e ("net: hns3: Add support of HNS3 Ethernet Driver for hip08 SoC")
Signed-off-by: Fuyun Liang <liangfuyun1@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>