batman-adv: Consolidate logging related functions

There are several places in batman-adv which provide logging related
functions. These should be grouped together in the log.* files to make them
easier to find.

Reported-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index b9c7325..a5b53a3 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -41,6 +41,7 @@
 #include "fragmentation.h"
 #include "hard-interface.h"
 #include "icmp_socket.h"
+#include "log.h"
 #include "network-coding.h"
 #include "originator.h"
 #include "packet.h"