HID: Remove unused function hid_is_using_ll_driver()

As the last user was removed we can delete this function.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: David Rheinsberg <david.rheinsberg@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

include/linux/hid.h

@@ -860,12 +860,6 @@ extern struct hid_ll_driver hidp_hid_driver;
 extern struct hid_ll_driver uhid_hid_driver;
 extern struct hid_ll_driver usb_hid_driver;
 
-static inline bool hid_is_using_ll_driver(struct hid_device *hdev,
-		struct hid_ll_driver *driver)
-{
-	return hdev->ll_driver == driver;
-}
-
 extern bool hid_is_usb(const struct hid_device *hdev);
 
 #define	PM_HINT_FULLON	1<<5