ASoC: Intel: avs: Add I2S-test machine board

Allow for testing audio streaming over I2S interface through SSP
loopback. No actual codec is needed here as board is intended for SSP
loopback scenarios only. One playback and one capture endpoint is
exposed per SSP port.

Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20220511162403.3987658-6-cezary.rojewski@intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>