net/udp: Add support for send() with connected UDP sockets

TODO

@@ -16,7 +16,7 @@ nuttx/
   (0)  Message Queues (sched/mqueue)
   (4)  C++ Support
   (6)  Binary loaders (binfmt/)
- (13)  Network (net/, drivers/net)
+ (12)  Network (net/, drivers/net)
   (4)  USB (drivers/usbdev, drivers/usbhost)
  (12)  Libraries (libc/, libm/)
  (11)  File system/Generic drivers (fs/, drivers/)
@@ -990,22 +990,6 @@ o Network (net/, drivers/net)
   Priority:    Low.  I don't know of any issues now, but I am sure that
                someone will encounter this in the future.
 
-  Title:       USING send() WITH UDP CONNECTIONS.
-  Description: Currently send is not implemented unless TCP is enabled.  If
-               TCP is enabled and send() is called with a UDP socket, send()
-               will fail with EDESTADDRREQ.  According to OpenGroup.org:
-
-                 "The send() function shall initiate transmission of a message
-                  from the specified socket to its peer. The send() function
-                  shall send a message only when the socket is connected
-                  (including when the peer of a connectionless socket has been
-                  set via connect()).
-
-               This means that, internally, send() should detect the "connected"
-               UDP socket and automatically call sendto().
-  Status:      Open
-  Priority:    Low, there is always the work-around of just calling sendto().
-
 o USB (drivers/usbdev, drivers/usbhost)
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^