NET: pass source IP address to packet handlers

This is needed for the upcoming TFTP server implementation.

This also simplifies PingHandler() and fixes rxhand_f documentation.

Signed-off-by: Luca Ceresoli <luca.ceresoli@comelit.it>
Cc: Wolfgang Denk <wd@denx.de>
Acked-by: Detlev Zundel <dzu@denx.de>
diff --git a/net/rarp.c b/net/rarp.c
index 9444c03..94c86d3 100644
--- a/net/rarp.c
+++ b/net/rarp.c
@@ -43,7 +43,8 @@
  *	Handle a RARP received packet.
  */
 static void
-RarpHandler(uchar * dummi0, unsigned dummi1, unsigned dummi2, unsigned dummi3)
+RarpHandler(uchar *dummi0, unsigned dummi1, IPaddr_t sip, unsigned dummi2,
+	    unsigned dummi3)
 {
 	char *s;
 	debug("Got good RARP\n");