net: wan: dlci: Remove set but not used variable 'err'

Fixes the following W=1 kernel build warning(s):

 drivers/net/wan/dlci.c: In function ‘dlci_close’:
 drivers/net/wan/dlci.c:298:8: warning: variable ‘err’ set but not used [-Wunused-but-set-variable]

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Mike McLagan <mike.mclagan@linux.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wan/dlci.c

@@ -295,14 +295,13 @@ static int dlci_close(struct net_device *dev)
 {
 	struct dlci_local	*dlp;
 	struct frad_local	*flp;
-	int			err;
 
 	netif_stop_queue(dev);
 
 	dlp = netdev_priv(dev);
 
 	flp = netdev_priv(dlp->slave);
-	err = (*flp->deactivate)(dlp->slave, dev);
+	(*flp->deactivate)(dlp->slave, dev);
 
 	return 0;
 }