fs tftp: use resolv to resolv ip address

instead of assuming the backingstore is a ip address, use resolv()
to make it possible to pass in a hostname.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

fs/tftp.c

@@ -603,7 +603,7 @@ static int tftp_probe(struct device_d *dev)
 
 	dev->priv = priv;
 
-	string_to_ip(fsdev->backingstore, &priv->server);
+	priv->server = resolv(fsdev->backingstore);
 
 	return 0;
 }