batman-adv: include gfp.h for GFP_* defines

The linux/gfp.h provides the GFP_ATOMIC and GFP_KERNEL define. It should
therefore be included instead of linux/fs.h.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
diff --git a/net/batman-adv/log.c b/net/batman-adv/log.c
index 148e64e..6fbcdd4 100644
--- a/net/batman-adv/log.c
+++ b/net/batman-adv/log.c
@@ -25,6 +25,7 @@
 #include <linux/export.h>
 #include <linux/fcntl.h>
 #include <linux/fs.h>
+#include <linux/gfp.h>
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/module.h>