Merge branch 'net-netpoll-remove-dead-code-and-speed-up-rtnl-locked-region'

Breno Leitao says:

====================
net: netpoll: remove dead code and speed up rtnl-locked region

This patchset introduces two minor modernizations to the netpoll
infrastructure:

The first patch removes the unused netpoll pointer from the netpoll_info
structure. This member is redundant and its presence does not benefit
multi-instance setups, as reported by Jay Vosburgh. Eliminating it cleans up
the structure and removes unnecessary code.

The second patch updates the netpoll resource cleanup routine to use
synchronize_net() instead of synchronize_rcu(). As __netpoll_free() is always
called under the RTNL lock, using synchronize_net() leverages the more
efficient synchronize_rcu_expedited() in these contexts, reducing time spent in
critical sections and improving performance.

Both changes simplify maintenance and enhance efficiency without altering
netpoll behavior.
====================

Link: https://patch.msgid.link/20250918-netpoll_jv-v1-0-67d50eeb2c26@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>