[PATCH V2] Add i.MX sound support

[Sascha Hauer]

Hi All,

Here is the second version of the patches to add i.MX sound support.

This time I haven't included ARM related patches, so this series should
be safe to apply.

I skipped the mc13783 driver since I'm not ready integrating the comments
from Mark.

The main change in the driver is that I splitted out the transport from
the driver, so it should be easy to add another transport layer to the
driver when SDMA support is merged. I hopefully also addressed the other
comments from Mark.

Sascha