Merge branch 'netpoll-code-organization-improvements'

Breno Leitao says:

====================
netpoll: Code organization improvements

The netpoll_setup() function has grown complex over time, mixing
different error handling and concerns like carrier waiting, IPv4 address
retrieval, and IPv6 address retrieval all within a single function,
which is huge (127 LoC).

This patch series refactors the netpoll_setup() function to improve code
organization and readability by extracting logical blocks into dedicated
helper functions. netpoll_setup() length is reduced to 72 LoC.

This series breaks down these responsibilities into focused helper
functions.

The changes are purely structural with no functional modifications.

This changes were tested with the netconsole tests and the netpoll
selftest (WIP)[1]

Link: https://lore.kernel.org/20250612-netpoll_test-v1-1-4774fd95933f@debian.org
====================

Link: https://patch.msgid.link/20250618-netpoll_ip_ref-v1-0-c2ac00fe558f@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>