drm/etnaviv: don't fail GPU bind when CONFIG_THERMAL isn't enabled

The stub functions returns -ENODEV when trying to register the cooling device,
thus failing the GPU bind, rendering the GPU subsystem unusable when
CONFIG_THERMAL isn't enabled.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

drivers/gpu/drm/etnaviv/etnaviv_gpu.c

@@ -1622,10 +1622,12 @@ static int etnaviv_gpu_bind(struct device *dev, struct device *master,
 	struct etnaviv_gpu *gpu = dev_get_drvdata(dev);
 	int ret;
 
-	gpu->cooling = thermal_of_cooling_device_register(dev->of_node,
+	if (IS_ENABLED(CONFIG_THERMAL)) {
+		gpu->cooling = thermal_of_cooling_device_register(dev->of_node,
 				(char *)dev_name(dev), gpu, &cooling_ops);
-	if (IS_ERR(gpu->cooling))
-		return PTR_ERR(gpu->cooling);
+		if (IS_ERR(gpu->cooling))
+			return PTR_ERR(gpu->cooling);
+	}
 
 #ifdef CONFIG_PM
 	ret = pm_runtime_get_sync(gpu->dev);