ARM: pxa: add support for Raumfeld audio devices [v2]

[Daniel Mack]

This is the second round of patches to add support for Raumfeld audio
devices. I hope to have addressed all issued that came up as response
to the first spin. If there's anything missing, please let me know.

I squashed most patches together now, hoping it's easier to review
this time.

Daniel

[PATCH 1/3] ARM: pxa/raumfeld: add platform support
[PATCH 2/3] ALSA: ARM: add Raumfeld audio support
[PATCH 3/3] ARM: pxa/raumfeld: Add defconfig