staging: axis-fifo: add error handling of class_create()

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/axis-fifo/axis-fifo.c

@@ -1089,6 +1089,8 @@ static int __init axis_fifo_init(void)
 	pr_info("axis-fifo driver loaded with parameters read_timeout = %i, write_timeout = %i\n",
 		read_timeout, write_timeout);
 	axis_fifo_driver_class = class_create(THIS_MODULE, DRIVER_NAME);
+	if (IS_ERR(axis_fifo_driver_class))
+		return PTR_ERR(axis_fifo_driver_class);
 	return platform_driver_register(&axis_fifo_driver);
 }