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>