media: mtk-vcodec: venc support MIN_OUTPUT_BUFFERS control

This control is required by v4l2-compliance for encoders. A value of 1
should be suitable for all scenarios.
Signed-off-by: Alexandre Courbot <acourbot@chromium.org>
Acked-by: Tiffany Lin <tiffany.lin@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-vcodec/mtk_vcodec_enc.c

@@ -1206,6 +1206,8 @@ int mtk_vcodec_enc_ctrls_setup(struct mtk_vcodec_ctx *ctx)
 
 	v4l2_ctrl_handler_init(handler, MTK_MAX_CTRLS_HINT);
 
+	v4l2_ctrl_new_std(handler, ops, V4L2_CID_MIN_BUFFERS_FOR_OUTPUT,
+			  1, 1, 1, 1);
 	v4l2_ctrl_new_std(handler, ops, V4L2_CID_MPEG_VIDEO_BITRATE,
 			  ctx->dev->venc_pdata->min_bitrate,
 			  ctx->dev->venc_pdata->max_bitrate, 1, 4000000);