net: hns3: fix for buffer overflow smatch warning

This patch fixes the buffer overflow warning by refactoring
hclgevf_bind_ring_to_vector and hclge_get_ring_chain_from_mbx.

Fixes: e2cb1dec ("net: hns3: Add HNS3 VF HCL(Hardware Compatibility Layer) Support")
Fixes: dde1a86e ("net: hns3: Add mailbox support to PF driver")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>