ASoC: hdac_hdmi: fix possible NULL dereference

kzalloc() can return NULL if it fails, and then we will be dereferencing
a NULL pointer.
Signed-off-by: NSudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: NMark Brown <broonie@kernel.org>

sound/soc/codecs/hdac_hdmi.c

@@ -200,6 +200,8 @@ static int hdac_hdmi_set_hw_params(struct snd_pcm_substream *substream,
 	}
 
 	dd = kzalloc(sizeof(*dd), GFP_KERNEL);
+	if (!dd)
+		return -ENOMEM;
 	dd->format = snd_hdac_calc_stream_format(params_rate(hparams),
 			params_channels(hparams), params_format(hparams),
 			24, 0);