ALSA: echoaudio: Mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Addresses-Coverity-ID: 115156 ("Missing break in switch")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/echoaudio/echoaudio.c

@@ -713,6 +713,7 @@ static int pcm_prepare(struct snd_pcm_substream *substream)
 		break;
 	case SNDRV_PCM_FORMAT_S32_BE:
 		format.data_are_bigendian = 1;
+		/* fall through */
 	case SNDRV_PCM_FORMAT_S32_LE:
 		format.bits_per_sample = 32;
 		break;
@@ -764,6 +765,7 @@ static int pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 					pipe->last_counter = 0;
 					pipe->position = 0;
 					*pipe->dma_counter = 0;
+					/* fall through */
 				case PIPE_STATE_PAUSED:
 					pipe->state = PIPE_STATE_STARTED;
 					break;