ASoC: intel: atom: Add period size constraint

Use constraint to make sure the period size could always be multiple
of 1ms to align with the fundamental design/limitation of firmware.

Signed-off-by: Brent Lu <brent.lu@intel.com>
Link: https://lore.kernel.org/r/1596198365-10105-2-git-send-email-brent.lu@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>