Adding addresses and ports to the short packet log message,
like ipv4/udp.c does it, makes these messages a lot more useful:

[  822.182450] UDPv6: short packet: From [2001:db8:ffb4:3::1]:47839 23715/178 to [2001:db8:ffb4:3:5054:ff:feff:200]:1234

This requires us to drop logging in case pskb_may_pull() fails,
which also is consistent with ipv4/udp.c
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>