ASoC: Intel: add NULL test

Add NULL test on call to devm_kzalloc.

The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
expression x;
identifier fld;
@@

* x = devm_kzalloc(...);
  ... when != x == NULL
  x->fld
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/baytrail/sst-baytrail-pcm.c

@@ -377,6 +377,8 @@ static int sst_byt_pcm_probe(struct snd_soc_platform *platform)
 
 	priv_data = devm_kzalloc(platform->dev, sizeof(*priv_data),
 				 GFP_KERNEL);
+	if (!priv_data)
+		return -ENOMEM;
 	priv_data->byt = plat_data->dsp;
 	snd_soc_platform_set_drvdata(platform, priv_data);