ASoC: imx: add missing module informations

- add some modules aliases
- add module license to avoid tainted kernel when loading the imx-pcm-audio
  driver

Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>