tipc: remove rcu_read_unlock() left in tipc_udp_recv()

I forgot to remove one rcu_read_unlock() before a return statement.

Joy of mixing goto and return styles in a function :)

Fixes: 4109a2c3 ("tipc: tipc_udp_recv() cleanup vs rcu verbs")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>