net: add struct net_aligned_data

This structure will hold networking data that must
consume a full cache line to avoid accidental false sharing.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250630093540.3052835-2-edumazet@google.com


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