Missing file change for previous driver-based UDP backlog from Max Holtzberg

net/recvfrom.c

@@ -953,6 +953,10 @@ static ssize_t udp_recvfrom(FAR struct socket *psock, FAR void *buf, size_t len,
 
       uip_udpenable(conn);
 
+      /* Notify the device driver of the receive call */
+
+      netdev_rxnotify(&conn->ripaddr);
+
       /* Wait for either the receive to complete or for an error/timeout to occur.
        * NOTES:  (1) uip_lockedwait will also terminate if a signal is received, (2)
        * interrupts are disabled!  They will be re-enabled while the task sleeps