libata: add printf format attribute to ehi desc functions

Tell the compiler that [__]ata_ehi_push_desc() functions take printf
style format string and arguments.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 86cc049..b89d191 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -948,8 +948,10 @@
 /*
  * ata_eh_info helpers
  */
-extern void __ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...);
-extern void ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...);
+extern void __ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
+	__attribute__ ((format (printf, 2, 3)));
+extern void ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
+	__attribute__ ((format (printf, 2, 3)));
 extern void ata_ehi_clear_desc(struct ata_eh_info *ehi);
 
 static inline void ata_ehi_schedule_probe(struct ata_eh_info *ehi)