udp: Remove udp_table in struct udp_seq_afinfo.

udp: Remove udp_table in struct udp_seq_afinfo.

Since UDP and UDP-Lite had dedicated socket hash tables for
each, we have had to fetch them from different pointers for
procfs or bpf iterator.

UDP always has its global or per-netns table in
net->ipv4.udp_table and struct udp_seq_afinfo.udp_table
is NULL.

OTOH, UDP-Lite had only one global table in the pointer.

We no longer use the field.

Let's remove it and udp_get_table_seq().

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260311052020.1213705-12-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>