ipv6: exthdrs: annotate data-race over multiple sysctl

ipv6: exthdrs: annotate data-race over multiple sysctl

[ Upstream commit 978b67d28358b0b4eacfa94453d1ad4e09b123ad ]

Following four sysctls can change under us, add missing READ_ONCE().

- ipv6.sysctl.max_dst_opts_len
- ipv6.sysctl.max_dst_opts_cnt
- ipv6.sysctl.max_hbh_opts_len
- ipv6.sysctl.max_hbh_opts_cnt

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260115094141.3124990-8-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>