drm/panfrost: Fix module unload

When unloading the call to pm_runtime_put_sync_suspend() will attempt to
turn the GPU cores off, however panfrost_device_fini() will have turned
the clocks off. This leads to the hardware locking up.

Instead don't call pm_runtime_put_sync_suspend() and instead simply mark
the device as suspended using pm_runtime_set_suspended(). And also
include this on the error path in panfrost_probe().

Fixes: aebe8c22 ("drm/panfrost: Fix possible suspend in panfrost_remove")
Signed-off-by: Steven Price <steven.price@arm.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201030145833.29006-1-steven.price@arm.com

drivers/gpu/drm/panfrost/panfrost_drv.c

@@ -626,6 +626,7 @@ static int panfrost_probe(struct platform_device *pdev)
 err_out1:
 	pm_runtime_disable(pfdev->dev);
 	panfrost_device_fini(pfdev);
+	pm_runtime_set_suspended(pfdev->dev);
 err_out0:
 	drm_dev_put(ddev);
 	return err;
@@ -640,9 +641,9 @@ static int panfrost_remove(struct platform_device *pdev)
 	panfrost_gem_shrinker_cleanup(ddev);
 
 	pm_runtime_get_sync(pfdev->dev);
-	panfrost_device_fini(pfdev);
-	pm_runtime_put_sync_suspend(pfdev->dev);
 	pm_runtime_disable(pfdev->dev);
+	panfrost_device_fini(pfdev);
+	pm_runtime_set_suspended(pfdev->dev);
 
 	drm_dev_put(ddev);
 	return 0;