Staging: quickstart: free after input_unregister_device()

input_unregister_device() releases "quickstart_input" so the
input_free_device() is a double free. Also I noticed that there is a
memory leak if the call to input_register_device() fails.

Signed-off-by: Dan Carpenter <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/quickstart/quickstart.c

···
 static void quickstart_exit(void)
 {
 	input_unregister_device(quickstart_input);
-	input_free_device(quickstart_input);
 
 	device_remove_file(&pf_device->dev, &dev_attr_pressed_button);
 	device_remove_file(&pf_device->dev, &dev_attr_buttons);
···
 {
 	struct quickstart_btn **ptr = &quickstart_data.btn_lst;
 	int count;
+	int ret;
 
 	quickstart_input = input_allocate_device();
 
···
 		ptr = &((*ptr)->next);
 	}
 
-	return input_register_device(quickstart_input);
+	ret = input_register_device(quickstart_input);
+	if (ret) {
+		input_free_device(quickstart_input);
+		return ret;
+	}
+
+	return 0;
 }
 
 static int __init quickstart_init(void)