TCP/IP controller: fixup a race between avahi and SVC hotplug

The TCP/IP controller was able to send a SVC hotplug operation to Greybus
before we get the host name, the IP and the port of the module.
Send the hotplug to Greybus only once avahi have completed the resolve
operation.

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>