sh: Replace an explicit computation by the use of the container_of macro

---
 arch/sh/kernel/cpu/irq/ipr.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
 
diff --git a/arch/sh/kernel/cpu/irq/ipr.c b/arch/sh/kernel/cpu/irq/ipr.c
index c1508a9..9282d96 100644
--- a/arch/sh/kernel/cpu/irq/ipr.c
+++ b/arch/sh/kernel/cpu/irq/ipr.c
@@ -17,16 +17,17 @@
  * for more details.
  */
 #include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
 #include <linux/irq.h>
+#include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/io.h>
-#include <linux/interrupt.h>
 #include <linux/topology.h>
 
 static inline struct ipr_desc *get_ipr_desc(unsigned int irq)
 {
 	struct irq_chip *chip = get_irq_chip(irq);
-	return (void *)((char *)chip - offsetof(struct ipr_desc, chip));
+	return container_of(chip, struct ipr_desc, chip);
 }
 
 static void disable_ipr_irq(unsigned int irq)