ASoC: imx-spdif: add snd_soc_pm_ops for spdif machine driver

Add snd_soc_pm_ops in machine driver to make the trigger suspend/resume
be called in suspend/resume.

Signed-off-by: Zidan Wang <zidan.wang@freescale.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/sound/soc/fsl/imx-spdif.c b/sound/soc/fsl/imx-spdif.c
index 33da26a..a407e83 100644
--- a/sound/soc/fsl/imx-spdif.c
+++ b/sound/soc/fsl/imx-spdif.c
@@ -89,6 +89,7 @@
 static struct platform_driver imx_spdif_driver = {
 	.driver = {
 		.name = "imx-spdif",
+		.pm = &snd_soc_pm_ops,
 		.of_match_table = imx_spdif_dt_ids,
 	},
 	.probe = imx_spdif_audio_probe,