ASoC: Intel: Atom: add definitions for modem/SSP0 interface

The Atom DPCM driver only allowed for the SSP2 interface, add
definitions for modem/SSP0.

These definitions might be used to route audio to a codec
connected to SSP0 (instead of a modem in traditional usages),
but there is a restriction to 2ch I2S. SSP2 is capable of
handling up to 4 slot TDM.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>