net: Update out-of-date comment

Struct inet_proto no longer exists, so update the
comment which is out of date.

Signed-off-by: Zhaowei Yuan <zhaowei.yuan@samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sock.h b/include/net/sock.h
index 3e82586..14d539c 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -926,7 +926,6 @@
 
 /* Networking protocol blocks we attach to sockets.
  * socket layer -> transport layer interface
- * transport -> network interface is defined by struct inet_proto
  */
 struct proto {
 	void			(*close)(struct sock *sk,