HID: fix memleaking of collection

hid_free_device() doesn't free device->collection (but it does
free device->rdesc and device itself). This imposes memory leak.
Fix it.

Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/hid-core.c

···
 	}
 
 	kfree(device->rdesc);
+	kfree(device->collection);
 	kfree(device);
 }
 EXPORT_SYMBOL_GPL(hid_free_device);