[DRIVER] fxl6408: add dts property gpio-base

drivers/gpio/gpio-fxl6408.c

@@ -221,12 +221,17 @@ static int fxl6408_probe(struct i2c_client *client,
 	gc->set_multiple = fxl6408_gpio_set_multiple;
 	gc->can_sleep = true;
 
-	gc->base =-1;
 	gc->ngpio = 8;
 	gc->label = chip->client->name;
 	gc->parent = dev;
 	gc->owner = THIS_MODULE;
 
+	gc->base = -1;
+	if (of_property_read_u32(dev->of_node, "gpio-base", &gpio_base) == 0) {
+		gc->base = gpio_base;
+		dev_info(dev, "GPIO expander base number will be %d\n", gpio_base);
+	}
+
 	ret = gpiochip_add_data(gc, chip);
 	if (ret)
 		return ret;