ALSA: pcm: Fix pcm_class sysfs output

The pcm_class sysfs of each PCM substream gives only "none" since the
recent code change to embed the struct device.  Fix the code to point
directly to the embedded device object properly.

Fixes: ef46c7af93 ('ALSA: pcm: Embed struct device')
Cc: <stable@vger.kernel.org> # v4.0+
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/pcm.c

@@ -1027,7 +1027,8 @@ void snd_pcm_detach_substream(struct snd_pcm_substream *substream)
 static ssize_t show_pcm_class(struct device *dev,
 			      struct device_attribute *attr, char *buf)
 {
-	struct snd_pcm *pcm;
+	struct snd_pcm_str *pstr = container_of(dev, struct snd_pcm_str, dev);
+	struct snd_pcm *pcm = pstr->pcm;
 	const char *str;
 	static const char *strs[SNDRV_PCM_CLASS_LAST + 1] = {
 		[SNDRV_PCM_CLASS_GENERIC] = "generic",
@@ -1036,8 +1037,7 @@ static ssize_t show_pcm_class(struct device *dev,
 		[SNDRV_PCM_CLASS_DIGITIZER] = "digitizer",
 	};
 
-	if (! (pcm = dev_get_drvdata(dev)) ||
-	    pcm->dev_class > SNDRV_PCM_CLASS_LAST)
+	if (pcm->dev_class > SNDRV_PCM_CLASS_LAST)
 		str = "none";
 	else
 		str = strs[pcm->dev_class];