[NETCONSOLE]: Clean up initcall warning.

From: Matt Mackall <mpm@selenic.com>

netconsole is being wrong here.  If it wasn't enabled there's no error.
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/netconsole.c

@@ -107,7 +107,7 @@ static int init_netconsole(void)
 
 	if(!configured) {
 		printk("netconsole: not configured, aborting\n");
-		return -EINVAL;
+		return 0;
 	}
 
 	if(netpoll_setup(&np))