Merge branch 'netns-init-cleanups' into main

Kuniyuki Iwashima says:

====================
net: Random cleanup for netns initialisation.

patch 1 & 2 suppress unwanted memory allocation for net->gen->ptr[].

patch 3 ~ 6 move part of netns initialisation to prenet_init() that
do not require pernet_ops_rwsem.

v2:
  patch 1 : Removed Fixes: tag
  patch 2 : Use XOR for WARN_ON()

v1: https://lore.kernel.org/netdev/20240729210801.16196-1-kuniyu@amazon.com/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>