batman-adv: split tvlv into a separate file

The tvlv functionality in main.c is mostly unrelated to the rest of the
content. It still takes up a large portion of this source file (~45%, 588
lines). Moving it to a separate file makes it better visible as a main
component of the batman-adv implementation and hides it less in the other
helper functions in main.c

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
[sven@narfation.org: fix conflicts with current version, fix includes,
rewrote commit message]
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

net/batman-adv/routing.c

@@ -46,6 +46,7 @@
 #include "send.h"
 #include "soft-interface.h"
 #include "translation-table.h"
+#include "tvlv.h"
 
 static int batadv_route_unicast_packet(struct sk_buff *skb,
 				       struct batadv_hard_iface *recv_if);