net: hns3: remove redundant return value of hns3_uninit_all_ring()

Since hns3_uninit_all_ring() only returns 0, so remove this
redundant return value and function declaration in hns3_enet.h.

Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>