qemu-char, io: fix ordering of arguments for UDP socket creation

Two wrongs make a right, but they should be fixed anyway.

Cc: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1455015557-15106-1-git-send-email-pbonzini@redhat.com>