Merge branch 'net-convert-atm-xdp-af_iucv-l2tp_ppp-rxrpc-tipc-to-getsockopt_iter'

Breno Leitao says:

====================
net: convert atm/xdp/af_iucv/l2tp_ppp/rxrpc/tipc to getsockopt_iter

This series continues the conversion of the remaining proto_ops getsockopt
callbacks to the new getsockopt_iter callback introduced in commit 67fab22a7adc
("net: add getsockopt_iter callback to proto_ops").

The new callback takes a sockopt_t — a type-safe wrapper around iov_iter
plus an optlen field — instead of raw __user pointers. This:

    - Replaces (char __user *optval, int __user *optlen) with sockopt_t *opt
    - Reads the input buffer size from opt->optlen instead of get_user()
    - Writes the option value via copy_to_iter() instead of copy_to_user()
    - Reports the returned length via opt->optlen instead of put_user(),
      independently of the bytes copied through the iter

Each conversion is a behaviour-preserving and code-style-preserving refactor;
no big changes being introduced, even when the code looks weird.
====================

Link: https://patch.msgid.link/20260520-getsock_four-v3-0-b8c0b16b7780@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>