Merge branch 'atm-remove-more-dead-code'

Jakub Kicinski says:

====================
atm: remove more dead code

Commit 6deb53595092 ("net: remove unused ATM protocols and legacy
ATM device drivers") removed a good chunk of old ATM drivers.
Our goal going forward is to limit the ATM support to PPPoATM
used in ADSL deployments.

A recent burst of AI generated fixes for net/atm/signaling.c and
net/atm/svc.c made me look closer at the remaining code. PPPoATM runs
over permanent virtual circuits (PF_ATMPVC) with a statically
configured VPI/VCI. We can drop switched virtual circuits (SVCs)
and user-space signaling (atmsigd) support. While digging around
I noticed a few more obviously dead pieces of code.

Annoyingly, I have applied one "fix" to QoS config which will
now make net conflict with this series :/
====================

Link: https://patch.msgid.link/20260615194416.752559-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>