udp: Clean up some functions.

udp: Clean up some functions.

[ Upstream commit 919dfa0b20ae56060dce0436eb710717f8987d18 ]

This patch adds no functional change and cleans up some functions
that the following patches touch around so that we make them tidy
and easy to review/revert.  The change is mainly to keep reverse
christmas tree order.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 7a7160edf1bf ("net: Return errno in sk->sk_prot->get_port().")
Signed-off-by: Sasha Levin <sashal@kernel.org>