Merge branch 'ax25-fix-issues-of-ax25_dev-and-net_device'

Duoming Zhou says:

====================
ax25: Fix issues of ax25_dev and net_device

The first patch uses kernel universal linked list to implement
ax25_dev_list, which makes the operation of the list easier.
The second and third patch fix reference count leak issues of
the object "ax25_dev" and "net_device".
====================

Link: https://lore.kernel.org/r/cover.1715247018.git.duoming@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>