intel_sst: MRST can only do 16bit recording

Fix bug

	$ arecord -D dsnoop -r 48000 -f S16_LE 1.wav
	ALSA lib pcm_direct.c:980:(snd1_pcm_direct_initialize_slave) unable to install hw params
	ALSA lib pcm_dsnoop.c:604:(snd_pcm_dsnoop_open) unable to initialize slave
	arecord: main:654: audio open error: Interrupted system call

Root cause is, the driver is reporting 32-bit capture capability
that is not supported by the MRST hardware. So the dsnoop plugin
end up requesting 32-bit capture which fails.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/intel_sst/intelmid.c

@@ -339,8 +339,11 @@ static int snd_intelmad_open(struct snd_pcm_substream *substream,
 		/*
 		 * MRST firmware currently denies stereo recording requests.
 		 */
-		if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
+		if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
+			runtime->hw.formats = (SNDRV_PCM_FMTBIT_S16 |
+					       SNDRV_PCM_FMTBIT_U16);
 			runtime->hw.channels_max = 1;
+		}
 	}
 	if (intelmaddata->cpu_id == CPU_CHIP_PENWELL) {
 		runtime->hw = snd_intelmad_stream;