ASoC: Revert 'ASoC: imx-ssi: Remove mono support'

Revert 0865a75d(ASoC: imx-ssi: Remove mono support).

The bug this patch is meant to solve doesn't occur in Visstrim_M10 boards.
Furthermore, after applying this patch sound in Visstrim_M10 is played
at slower rates.
Signed-off-by: Javier Martin <javier.martin@vista-silicon.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/fsl/imx-ssi.c

@@ -380,14 +380,13 @@ static int imx_ssi_dai_probe(struct snd_soc_dai *dai)
 static struct snd_soc_dai_driver imx_ssi_dai = {
 	.probe = imx_ssi_dai_probe,
 	.playback = {
-		/* The SSI does not support monaural audio. */
-		.channels_min = 2,
+		.channels_min = 1,
 		.channels_max = 2,
 		.rates = SNDRV_PCM_RATE_8000_96000,
 		.formats = SNDRV_PCM_FMTBIT_S16_LE,
 	},
 	.capture = {
-		.channels_min = 2,
+		.channels_min = 1,
 		.channels_max = 2,
 		.rates = SNDRV_PCM_RATE_8000_96000,
 		.formats = SNDRV_PCM_FMTBIT_S16_LE,