batman-adv: Add const type qualifier for pointers

batman-adv uses pointers which are marked as const and should not
violate that type qualifier by passing it to functions which force a
cast to the non-const version.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
diff --git a/net/batman-adv/bat_debugfs.c b/net/batman-adv/bat_debugfs.c
index 628ab18..1049ae3 100644
--- a/net/batman-adv/bat_debugfs.c
+++ b/net/batman-adv/bat_debugfs.c
@@ -51,7 +51,7 @@
 }
 
 __printf(2, 3)
-static int fdebug_log(struct debug_log *debug_log, char *fmt, ...)
+static int fdebug_log(struct debug_log *debug_log, const char *fmt, ...)
 {
 	va_list args;
 	static char debug_log_buf[256];
@@ -75,7 +75,7 @@
 	return 0;
 }
 
-int debug_log(struct bat_priv *bat_priv, char *fmt, ...)
+int debug_log(struct bat_priv *bat_priv, const char *fmt, ...)
 {
 	va_list args;
 	char tmp_log_buf[256];