Restore the peer addresses in P2P mode.

Commit ea7a7882 removed the calls to transport_peer(), inadvertently
substituting them with transport_send(), resulting in PDelay messages
being sent with an incorrect destination address.

This patch fixes the issue by introducing peer_prepare_and_send(),
analogous to the port_prepare_and_send() function.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Jiri Benc <jbenc@redhat.com>