net: hns3: add debugfs support for ptp info

mainline inclusion
from mainline-master
commit b34c157f
category: feature
bugzilla: 173966
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b34c157f0cdd0b9e52c002288ff77b1a553dd438



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Add a debugfs interface for dumping ptp information, which
is helpful for debugging.

Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: Yufeng Mo <moyufeng@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Reviewed-by: Yongxin Li <liyongxin1@huawei.com>
Signed-off-by: Junxin Chen <chenjunxin1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>