media: mediatek: vcodec: Handle invalid encoder vsi

Handle invalid encoder vsi in vpu_enc_init to ensure the encoder
vsi is valid for future use.

Fixes: 1972e324 ("media: mediatek: vcodec: Fix possible invalid memory access for encoder")
Signed-off-by: Irui Wang <irui.wang@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/media/platform/mediatek/vcodec/encoder/venc_vpu_if.c

@@ -153,6 +153,11 @@ int vpu_enc_init(struct venc_vpu_inst *vpu)
 		return -EINVAL;
 	}
 
+	if (IS_ERR_OR_NULL(vpu->vsi)) {
+		mtk_venc_err(vpu->ctx, "invalid venc vsi");
+		return -EINVAL;
+	}
+
 	return 0;
 }