net: hns3: refactor the debugfs process

Currently, each debugfs command needs to create a file to get
the information. To better support more debugfs commands, the
debugfs process is reconstructed, including the process of
creating dentries and files, and obtaining information.

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