ASoC: Intel: Atom: fix regression on compress DAI

Commit a1068045 ("ASoC: compress: Fix compress device direction check")
added a dependency on the compress-cpu-dai channel_min field
which was removed earlier by commit 77095796
("ASoC: Intel: Atom: clean-up compressed DAI definition")
as part of the baytrail cleanups.

The net result was a regression at probe on all Atom platforms
with no sound card created.

Fix by adding explicit initialization for channel_min to 1
for the compress-cpu-dai.
Reported-by: Tobias Mädel <alsa-devel@tbspace.de>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/atom/sst-mfld-platform-pcm.c

@@ -528,6 +528,7 @@ static struct snd_soc_dai_driver sst_platform_dai[] = {
 	.ops = &sst_compr_dai_ops,
 	.playback = {
 		.stream_name = "Compress Playback",
+		.channels_min = 1,
 	},
 },
 /* BE CPU  Dais */