NET: slip, fix ldisc->open retval

TTY layer expects 0 if the ldisc->open operation succeeded.

Signed-off-by : Matvejchikov Ilya <matvejchikov@gmail.com>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Acked-by: Alan Cox <alan@linux.intel.com>

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/slip.c b/drivers/net/slip.c
index 86cbb9e..8ec1a9a 100644
--- a/drivers/net/slip.c
+++ b/drivers/net/slip.c
@@ -853,7 +853,9 @@
 	/* Done.  We have linked the TTY line to a channel. */
 	rtnl_unlock();
 	tty->receive_room = 65536;	/* We don't flow control */
-	return sl->dev->base_addr;
+
+	/* TTY layer expects 0 on success */
+	return 0;
 
 err_free_bufs:
 	sl_free_bufs(sl);