Merge branch 'udp_tunnel-remove-rtnl_lock-dependency'

Stanislav Fomichev says:

====================
udp_tunnel: remove rtnl_lock dependency

Recently bnxt had to grow back a bunch of rtnl dependencies because
of udp_tunnel's infra. Add separate (global) mutext to protect
udp_tunnel state.
====================

Link: https://patch.msgid.link/20250616162117.287806-1-stfomichev@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>