ALSA: pcm: Fix superfluous snprintf() usage

show_pcm_class() returns obviously a short string that can't overflow
PAGE_SIZE.  And even if it were to overflow, using snprintf() there is
just wrong, as it doesn't return the correct size.
So simplify with sprintf() instead.

Link: https://lore.kernel.org/r/20200313130223.8908-1-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/pcm.c

@@ -1019,7 +1019,7 @@ static ssize_t show_pcm_class(struct device *dev,
 		str = "none";
 	else
 		str = strs[pcm->dev_class];
-        return snprintf(buf, PAGE_SIZE, "%s\n", str);
+	return sprintf(buf, "%s\n", str);
 }
 
 static DEVICE_ATTR(pcm_class, 0444, show_pcm_class, NULL);