atm: remove orphaned uAPI for deleted drivers, protocols and SVCs

atm: remove orphaned uAPI for deleted drivers, protocols and SVCs

ATM removals have left a number of uAPI headers and ioctl
definitions with no in-kernel implementation behind them:

 - device headers for adapters deleted with the legacy PCI/SBUS drivers:
   atm_eni.h, atm_he.h, atm_idt77105.h, atm_nicstar.h, atm_zatm.h and
   the atmtcp pair atm_tcp.h / <linux/atm_tcp.h>
 - protocol headers for the removed CLIP, LANE and MPOA stacks:
   atmarp.h, atmclip.h, atmlec.h, atmmpc.h
 - atmsvc.h and the SVC / p2mp / local-address ioctls in atmdev.h
   (ATM_{GET,RST,ADD,DEL}ADDR, ATM_{ADD,DEL,GET}LECSADDR,
   ATM_{ADD,DROP}PARTY) left behind by the SVC and address-registry
   removals

None of these are referenced by any remaining in-tree code.
Let's try to delete all this. Chances are nobody cares about
these headers any more. I'm keeping this separate from the
kernel side code changes for ease of revert, in case I am
proven wrong...

Link: https://patch.msgid.link/20260615194416.752559-10-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>