sfc: Remove redundant casts to and from void *

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index 11ee0d4..4497606 100644
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -1490,7 +1490,7 @@
 static int efx_netdev_event(struct notifier_block *this,
 			    unsigned long event, void *ptr)
 {
-	struct net_device *net_dev = (struct net_device *)ptr;
+	struct net_device *net_dev = ptr;
 
 	if (net_dev->open == efx_net_open && event == NETDEV_CHANGENAME) {
 		struct efx_nic *efx = net_dev->priv;