HID: use kobj_to_dev()

Use kobj_to_dev() instead of open-coding it.

Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-roccat-lua.c b/drivers/hid/hid-roccat-lua.c
index 65e2e76..ac1a731 100644
--- a/drivers/hid/hid-roccat-lua.c
+++ b/drivers/hid/hid-roccat-lua.c
@@ -30,7 +30,7 @@
 		char *buf, loff_t off, size_t count,
 		size_t real_size, uint command)
 {
-	struct device *dev = container_of(kobj, struct device, kobj);
+	struct device *dev = kobj_to_dev(kobj);
 	struct lua_device *lua = hid_get_drvdata(dev_get_drvdata(dev));
 	struct usb_device *usb_dev = interface_to_usbdev(to_usb_interface(dev));
 	int retval;
@@ -52,7 +52,7 @@
 		void const *buf, loff_t off, size_t count,
 		size_t real_size, uint command)
 {
-	struct device *dev = container_of(kobj, struct device, kobj);
+	struct device *dev = kobj_to_dev(kobj);
 	struct lua_device *lua = hid_get_drvdata(dev_get_drvdata(dev));
 	struct usb_device *usb_dev = interface_to_usbdev(to_usb_interface(dev));
 	int retval;