drm/panfrost: Disable PM on probe failure

Make sure to disable runtime PM again if probe fails after we've enabled
it. Otherwise, any subsequent attempt to re-probe starts triggering
"Unbalanced pm_runtime_enable!" assertions from the driver core.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/2487391e7646cabbc52e9b4c20182e39d3f61859.1556195258.git.robin.murphy@arm.com

drivers/gpu/drm/panfrost/panfrost_drv.c

@@ -418,6 +418,7 @@ static int panfrost_probe(struct platform_device *pdev)
 err_out1:
 	panfrost_device_fini(pfdev);
 err_out0:
+	pm_runtime_disable(pfdev->dev);
 	drm_dev_put(ddev);
 	return err;
 }