connector: make callback argument type explicit

The connector documentation states that the argument to the callback
function is always a pointer to a struct cn_msg, but rather than encode it
in the API itself, it uses a void pointer everywhere.  This doesn't make
much sense to encode the pointer in documentation as it prevents proper C
type checking from occurring and can easily allow people to use the wrong
pointer type.  So convert the argument type to an explicit struct cn_msg
pointer.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/w1/w1_netlink.c b/drivers/w1/w1_netlink.c
index fdf7285..52ccb3d 100644
--- a/drivers/w1/w1_netlink.c
+++ b/drivers/w1/w1_netlink.c
@@ -306,9 +306,8 @@
 	return error;
 }
 
-static void w1_cn_callback(void *data)
+static void w1_cn_callback(struct cn_msg *msg)
 {
-	struct cn_msg *msg = data;
 	struct w1_netlink_msg *m = (struct w1_netlink_msg *)(msg + 1);
 	struct w1_netlink_cmd *cmd;
 	struct w1_slave *sl;