From: Herton R. Krzesinski on
gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/issues/46#note_566395197
In the case of sctp, sctp_diag is on kernel-modules and is pulling sctp
back to it. The fix is to add sctp_diag to the mod-extra.list.
In the case of the l2tp* modules, the l2tp_ip6 is pulling l2tp_core and
l2tp_ip into kernel-modules. THe fix is to add l2tp_ip6 to mod-
extra.list.