net: move sysctl_skb_defer_max to net_hotdata

sysctl_skb_defer_max is used in TCP fast path,
move it to net_hodata.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20240429134025.1233626-3-edumazet@google.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>