ALSA: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200708203236.GA5112@embeddedor
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 1e51c84..9e0b2d7 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1903,7 +1903,7 @@ static int snd_pcm_prepare(struct snd_pcm_substream *substream,
 	switch (substream->runtime->status->state) {
 	case SNDRV_PCM_STATE_PAUSED:
 		snd_pcm_pause(substream, false);
-		/* fallthru */
+		fallthrough;
 	case SNDRV_PCM_STATE_SUSPENDED:
 		snd_pcm_stop(substream, SNDRV_PCM_STATE_SETUP);
 		break;
@@ -2811,7 +2811,7 @@ static int do_pcm_hwsync(struct snd_pcm_substream *substream)
 	case SNDRV_PCM_STATE_DRAINING:
 		if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
 			return -EBADFD;
-		/* Fall through */
+		fallthrough;
 	case SNDRV_PCM_STATE_RUNNING:
 		return snd_pcm_update_hw_ptr(substream);
 	case SNDRV_PCM_STATE_PREPARED:
@@ -3814,7 +3814,7 @@ static int snd_pcm_mmap(struct file *file, struct vm_area_struct *area)
 	case SNDRV_PCM_MMAP_OFFSET_STATUS_OLD:
 		if (pcm_file->no_compat_mmap || !IS_ENABLED(CONFIG_64BIT))
 			return -ENXIO;
-		/* fallthrough */
+		fallthrough;
 	case SNDRV_PCM_MMAP_OFFSET_STATUS_NEW:
 		if (!pcm_status_mmap_allowed(pcm_file))
 			return -ENXIO;
@@ -3822,7 +3822,7 @@ static int snd_pcm_mmap(struct file *file, struct vm_area_struct *area)
 	case SNDRV_PCM_MMAP_OFFSET_CONTROL_OLD:
 		if (pcm_file->no_compat_mmap || !IS_ENABLED(CONFIG_64BIT))
 			return -ENXIO;
-		/* fallthrough */
+		fallthrough;
 	case SNDRV_PCM_MMAP_OFFSET_CONTROL_NEW:
 		if (!pcm_control_mmap_allowed(pcm_file))
 			return -ENXIO;