ASoC: Intel: boards: replace capture_only by dpcm_capture

It's not clear why specific FE dailinks use capture_only flags, likely
blind copy/paste from Chromebook driver to the other.  Replace by
dpcm_capture, this will make future alignment and removal of flags
easier.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Daniel Baluta <daniel.baluta@gmail.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20200608194415.4663-4-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>