Documentation: driver-api: update kernel connector

This patch changes:
1) Fix typo in kernel connector documentation.
	s/cn_netlink_send_multi/cn_netlink_send_mult/
2) update definition of struct cn_msg
Signed-off-by: Wang Long <w@laoqinren.net>
Link: https://lore.kernel.org/r/1595229852-114071-1-git-send-email-w@laoqinren.netSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/driver-api/connector.rst

@@ -26,7 +26,7 @@ netlink based networking for inter-process communication in a significantly
 easier way::
 
   int cn_add_callback(struct cb_id *id, char *name, void (*callback) (struct cn_msg *, struct netlink_skb_parms *));
-  void cn_netlink_send_multi(struct cn_msg *msg, u16 len, u32 portid, u32 __group, int gfp_mask);
+  void cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 __group, int gfp_mask);
   void cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group, int gfp_mask);
 
   struct cb_id
@@ -48,7 +48,8 @@ be dereferenced to `struct cn_msg *`::
 	__u32			seq;
 	__u32			ack;
 
-	__u32			len;	/* Length of the following data */
+	__u16			len;	/* Length of the following data */
+	__u16			flags;
 	__u8			data[0];
   };