net: hns3: refactor dev capability and dev spec of debugfs

Currently, the debugfs command for dev capability and dev spec
are implemented by "echo xxxx > cmd", and record the information
in dmesg. It's unnecessary and heavy. To improve it, create a
single file "dev_info" for them, and query them by command
"cat dev_info", return the result to userspace, rather than
record in dmesg.

The display style is below:
$cat dev_info
dev capability:
support FD: yes
support GRO: yes
support FEC: yes
support UDP GSO: no
support PTP: no
support INT QL: no
support HW TX csum: no
support UDP tunnel csum: no
support TX push: no
support imp-controlled PHY: no
support rxd advanced layout: no

dev spec:
MAC entry num: 0
MNG entry num: 0
MAX non tso bd num: 8
RSS ind tbl size: 512
RSS key size: 40
RSS size: 1
Allocated RSS size: 0
Task queue pairs numbers: 1
RX buffer length: 2048
Desc num per TX queue: 1024
Desc num per RX queue: 1024
Total number of enabled TCs: 1
MAX INT QL: 0
MAX INT GL: 8160
MAX TM RATE: 100000
MAX QSET number: 1024

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