Make sure that labeling is used consistently in all function headers.

net/pkt/pkt.h

@@ -193,7 +193,7 @@ uint16_t pkt_callback(FAR struct net_driver_s *dev,
  * Parameters:
  *   dev - The device driver structure containing the received packet
  *
- * Return:
+ * Returned Value:
  *   OK    The packet has been processed  and can be deleted
  *   ERROR There is a matching connection, but could not dispatch the packet
  *         yet.  Useful when a packet arrives before a recv call is in
@@ -267,7 +267,7 @@ FAR struct net_driver_s *pkt_find_device(FAR struct pkt_conn_s *conn);
  *   dev - The device driver structure to use in the send operation
  *   conn - The packet "connection" to poll for TX data
  *
- * Return:
+ * Returned Value:
  *   None
  *
  * Assumptions:

net/pkt/pkt_input.c

@@ -73,7 +73,7 @@
  * Parameters:
  *   dev - The device driver structure containing the received packet
  *
- * Return:
+ * Returned Value:
  *   OK    The packet has been processed  and can be deleted
  *   ERROR There is a matching connection, but could not dispatch the packet
  *         yet.  Useful when a packet arrives before a recv call is in

net/pkt/pkt_poll.c

@@ -68,7 +68,7 @@
  *   dev - The device driver structure to use in the send operation
  *   conn - The packet "connection" to poll for TX data
  *
- * Return:
+ * Returned Value:
  *   None
  *
  * Assumptions:

net/pkt/pkt_recvfrom.c

@@ -159,7 +159,7 @@ static void pkt_recvfrom_newdata(FAR struct net_driver_s *dev,
  *
  * Parameters:
  *
- * Returned Values:
+ * Returned Value:
  *
  * Assumptions:
  *
@@ -177,7 +177,7 @@ static inline void pkt_recvfrom_sender(FAR struct net_driver_s *dev,
  *
  * Parameters:
  *
- * Returned Values:
+ * Returned Value:
  *
  * Assumptions:
  *