ath6kl: Add __printf verification to ath6kl_printk

Make sure printf formats and arguments match.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath6kl/common.h

@@ -22,7 +22,8 @@
 
 #define ATH6KL_MAX_IE			256
 
-extern int ath6kl_printk(const char *level, const char *fmt, ...);
+extern __printf(2, 3)
+int ath6kl_printk(const char *level, const char *fmt, ...);
 
 /*
  * Reflects the version of binary interface exposed by ATH6KL target