ALSA: Replace with fallthrough pseudo keyword in the remaining places

A few places (except for ASoC) are left unconverted for the new
fallthrough pseudo keyword.  Now replace them all.

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200709111750.8337-4-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/oxygen/oxygen_pcm.c

@@ -137,7 +137,7 @@ static int oxygen_open(struct snd_pcm_substream *substream,
 					       SNDRV_PCM_RATE_64000);
 			runtime->hw.rate_min = 44100;
 		}
-		/* fall through */
+		fallthrough;
 	case PCM_A:
 	case PCM_B:
 		runtime->hw.fifo_size = 0;