media: stm32-dcmi: fix check of pm_runtime_get_sync return value

Start streaming was sometimes failing because of pm_runtime_get_sync()
non-0 return value. In fact return value was not an error but a
positive value (1), indicating that PM was already enabled.
Fix this by going to error path only with negative return value.
Signed-off-by: Hugues Fruchet <hugues.fruchet@st.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/stm32/stm32-dcmi.c

@@ -570,9 +570,9 @@ static int dcmi_start_streaming(struct vb2_queue *vq, unsigned int count)
 	int ret;
 
 	ret = pm_runtime_get_sync(dcmi->dev);
-	if (ret) {
-		dev_err(dcmi->dev, "%s: Failed to start streaming, cannot get sync\n",
-			__func__);
+	if (ret < 0) {
+		dev_err(dcmi->dev, "%s: Failed to start streaming, cannot get sync (%d)\n",
+			__func__, ret);
 		goto err_release_buffers;
 	}