ASoC: spdif-dit: Add missing MODULE_*

MODULE_ALIAS is required so that the module will auto-load based on a
platform_device registration in the board file.

While we're at it, add some other MODULE_*.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>