udp: Don't pass udptable to IPv4 socket lookup functions.

udp: Don't pass udptable to IPv4 socket lookup functions.

Since UDP and UDP-Lite had dedicated socket hash tables for
each, we have had to pass the pointer down to many socket
lookup functions.

UDP-Lite gone, and we do not need to do that.

Let's fetch net->ipv4.udp_table only where needed in IPv4
stack: __udp4_lib_lookup(), __udp4_lib_mcast_deliver(),
and udp_diag_dump().

Some functions are renamed as the wrapper functions are no
longer needed.

  __udp4_lib_err()     -> udp_err()
  __udp_diag_destroy() -> udp_diag_destroy()
  udp_dump_one()       -> udp_diag_dump_one()
  udp_dump()           -> udp_diag_dump()

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260311052020.1213705-15-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>