net: Unregister net_default_ip and net_default_mac variables hooks on unload

net: Unregister net_default_ip and net_default_mac variables hooks on unload

The net module is a dependency of normal. So, it shouldn't be possible
to unload the net. Though unregister variables hooks as a precaution.
It also gets in line with unregistering the other net module hooks.

Signed-off-by: B Horn <b@horn.uk>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Gbp-Pq: Topic cve-2025-jan
Gbp-Pq: Name net-Unregister-net_default_ip-and-net_default_mac-variabl.patch