ALSA: core: add support for compressed devices

Use the minor numbers 2 and 3 for audio compressed offload devices.
Also add support for these devices in core

Signed-off-by: Omair Mohammed Abdullah <omair.m.abdullah@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/sound.c b/sound/core/sound.c
index 828af35..28f3559 100644
--- a/sound/core/sound.c
+++ b/sound/core/sound.c
@@ -229,6 +229,7 @@
 	case SNDRV_DEVICE_TYPE_RAWMIDI:
 	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
 	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
+	case SNDRV_DEVICE_TYPE_COMPRESS:
 		if (snd_BUG_ON(!card))
 			return -EINVAL;
 		minor = SNDRV_MINOR(card->number, type + dev);