drm/panfrost: Fix runtime PM imbalance on error

The caller expects panfrost_job_hw_submit() to increase
runtime PM usage counter. The refcount decrement on the
error branch of WARN_ON() will break the counter balance
and needs to be removed.
Signed-off-by: NDinghao Liu <dinghao.liu@zju.edu.cn>
Reviewed-by: NSteven Price <steven.price@arm.com>
Signed-off-by: NSteven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200522134109.27204-1-dinghao.liu@zju.edu.cn

drivers/gpu/drm/panfrost/panfrost_job.c

@@ -152,7 +152,6 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
 		return;
 
 	if (WARN_ON(job_read(pfdev, JS_COMMAND_NEXT(js)))) {
-		pm_runtime_put_sync_autosuspend(pfdev->dev);
 		return;
 	}