[IRDA]: Compilation for CONFIG_INET=n case

Found this occasionally.

The CONFIG_INET=n is hardly ever set, but if it is the
irlan_eth_send_gratuitous_arp() compilation should produce a
warning about unused variable in_dev.

Too pedantic? :)

Signed-off-by: Pavel Emelyanov <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

net/irda/irlan/irlan_eth.c

···
  */
 void irlan_eth_send_gratuitous_arp(struct net_device *dev)
 {
+#ifdef CONFIG_INET
 	struct in_device *in_dev;
 
 	/*
···
 	 * is useful if we have changed access points on the same
 	 * subnet.
 	 */
-#ifdef CONFIG_INET
 	IRDA_DEBUG(4, "IrLAN: Sending gratuitous ARP\n");
 	rcu_read_lock();
 	in_dev = __in_dev_get_rcu(dev);