rapidio: use kobj_to_dev()

Use kobj_to_dev() instead of open-coding it.
Signed-off-by: Geliang Tang <geliangtang@163.com>
Acked-by: "Bounine, Alexandre" <Alexandre.Bounine@idt.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rapidio/rio-sysfs.c

@@ -125,8 +125,7 @@ rio_read_config(struct file *filp, struct kobject *kobj,
 		struct bin_attribute *bin_attr,
 		char *buf, loff_t off, size_t count)
 {
-	struct rio_dev *dev =
-	    to_rio_dev(container_of(kobj, struct device, kobj));
+	struct rio_dev *dev = to_rio_dev(kobj_to_dev(kobj));
 	unsigned int size = 0x100;
 	loff_t init_off = off;
 	u8 *data = (u8 *) buf;
@@ -197,8 +196,7 @@ rio_write_config(struct file *filp, struct kobject *kobj,
 		 struct bin_attribute *bin_attr,
 		 char *buf, loff_t off, size_t count)
 {
-	struct rio_dev *dev =
-	    to_rio_dev(container_of(kobj, struct device, kobj));
+	struct rio_dev *dev = to_rio_dev(kobj_to_dev(kobj));
 	unsigned int size = count;
 	loff_t init_off = off;
 	u8 *data = (u8 *) buf;