media: platform: Improve subscribe event flow for bug fixing

Let v4l2_ctrl_subscribe_event() do the job for other types except
V4L2_EVENT_SOURCE_CHANGE.
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Xia Jiang <xia.jiang@mediatek.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/platform/mtk-jpeg/mtk_jpeg_core.c

@@ -446,9 +446,9 @@ static int mtk_jpeg_subscribe_event(struct v4l2_fh *fh,
 	switch (sub->type) {
 	case V4L2_EVENT_SOURCE_CHANGE:
 		return v4l2_src_change_event_subscribe(fh, sub);
-	default:
-		return -EINVAL;
 	}
+
+	return v4l2_ctrl_subscribe_event(fh, sub);
 }
 
 static int mtk_jpeg_g_selection(struct file *file, void *priv,