ALSA: pcm: add SNDRV_PCM_FORMAT_{S,U}20

This format is similar to existing SNDRV_PCM_FORMAT_{S,U}20_3 that keep
20-bit PCM samples in 3 bytes, however i.MX6 platform SSI FIFO does not
allow 3-byte accesses (including DMA) so a 4-byte (more conventional)
format is needed for it.

Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/include/sound/soc-dai.h b/include/sound/soc-dai.h
index 58acd00..d970879 100644
--- a/include/sound/soc-dai.h
+++ b/include/sound/soc-dai.h
@@ -102,6 +102,8 @@ struct snd_compr_stream;
 			       SNDRV_PCM_FMTBIT_S16_BE |\
 			       SNDRV_PCM_FMTBIT_S20_3LE |\
 			       SNDRV_PCM_FMTBIT_S20_3BE |\
+			       SNDRV_PCM_FMTBIT_S20_LE |\
+			       SNDRV_PCM_FMTBIT_S20_BE |\
 			       SNDRV_PCM_FMTBIT_S24_3LE |\
 			       SNDRV_PCM_FMTBIT_S24_3BE |\
                                SNDRV_PCM_FMTBIT_S32_LE |\