HID: add a new helper to_hid_driver()

Add a new helper to_hid_driver() and use it in hid-core.c.

Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 1472026..75b66ec 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -717,6 +717,9 @@
 	struct device_driver driver;
 };
 
+#define to_hid_driver(pdrv) \
+	container_of(pdrv, struct hid_driver, driver)
+
 /**
  * hid_ll_driver - low level driver callbacks
  * @start: called on probe to start the device