net: app: Use port when init server with both IPv4 and IPv6

If we have specified AF_UNSPEC when initializing application
server local address, then we try to bind to both IPv4 and IPv6
addresses. The old code did not honor the port number in this
case but used some random value for port.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>