Merge branch 'ipv6-drop-rtnl-from-mcast-c-and-anycast-c'

Kuniyuki Iwashima says:

====================
ipv6: Drop RTNL from mcast.c and anycast.c

This is a prep series for RCU conversion of RTM_NEWNEIGH, which needs
RTNL during neigh_table.{pconstructor,pdestructor}() touching IPv6
multicast code.

Currently, IPv6 multicast code is protected by lock_sock() and
inet6_dev->mc_lock, and RTNL is not actually needed.

In addition, anycast code is also in the same situation and does not
need RTNL at all.

This series removes RTNL from net/ipv6/{mcast.c,anycast.c} and finally
removes setsockopt_needs_rtnl() from do_ipv6_setsockopt().

v2: https://lore.kernel.org/20250624202616.526600-1-kuni1840@gmail.com
v1: https://lore.kernel.org/20250616233417.1153427-1-kuni1840@gmail.com
====================

Link: https://patch.msgid.link/20250702230210.3115355-1-kuni1840@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>