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/tftp.c b/net/tftp.c
index ed559b7..00abec3 100644
--- a/net/tftp.c
+++ b/net/tftp.c
@@ -278,7 +278,8 @@
 
 
 static void
-TftpHandler (uchar * pkt, unsigned dest, unsigned src, unsigned len)
+TftpHandler(uchar *pkt, unsigned dest, IPaddr_t sip, unsigned src,
+	    unsigned len)
 {
 	ushort proto;
 	ushort *s;