net: hns3: fix the concurrency between functions reading debugfs

Currently, the debugfs mechanism is that all functions share a
global variable to save the pointer for obtaining data. When
different functions concurrently access the same file node,
repeated release exceptions occur. Therefore, the granularity
of the pointer for storing the obtained data is adjusted to be
private for each function.

Fixes: 5e69ea7e

 ("net: hns3: refactor the debugfs process")
Signed-off-by: Yufeng Mo <moyufeng@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>