net: remove unused ATM protocols and legacy ATM device drivers

net: remove unused ATM protocols and legacy ATM device drivers

Remove the ATM protocol modules and PCI/SBUS ATM device drivers
that are no longer in active use.

The ATM core protocol stack, PPPoATM, BR2684, and USB DSL modem
drivers (drivers/usb/atm/) are retained in-tree to maintain PPP
over ATM (PPPoA) and PPPoE-over-BR2684 support for DSL connections.
The Solos ADSL2+ PCI driver is also retained.

Removed ATM protocol modules:
 - net/atm/clip.c - Classical IP over ATM (RFC 2225)
 - net/atm/lec.c - LAN Emulation Client (LANE)
 - net/atm/mpc.c, mpoa_caches.c, mpoa_proc.c - Multi-Protocol Over ATM

Removed PCI/SBUS ATM device drivers (drivers/atm/):
 - adummy, atmtcp - software/testing ATM devices
 - eni - Efficient Networks ENI155P (OC-3, ~1995)
 - fore200e - FORE Systems 200E PCI/SBUS (OC-3, ~1999)
 - he - ForeRunner HE (OC-3/OC-12, ~2000)
 - idt77105 - IDT 77105 25 Mbps ATM PHY
 - idt77252 - IDT 77252 NICStAR II (OC-3, ~2000)
 - iphase - Interphase ATM PCI (OC-3/DS3/E3)
 - lanai - Efficient Networks Speedstream 3010
 - nicstar - IDT 77201 NICStAR (155/25 Mbps, ~1999)
 - suni - PMC S/UNI SONET PHY library

Also clean up references in:
 - net/bridge/ - remove ATM LANE hook (br_fdb_test_addr_hook,
   br_fdb_test_addr)
 - net/core/dev.c - remove br_fdb_test_addr_hook export
 - defconfig files - remove ATM driver config options

The removed code is moved to an out-of-tree module package (mod-orphan).

Acked-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20260422041846.2035118-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>