[ALSA] snd-emu10k1: Removes some distortion from Audigy 2 ZS Notebook.

Modules: EMU10K1/EMU10K2 driver

Description:
Part way to fix ALSA bug#927
Add support for the SPI interface on the CA0108 chip.
This is used to control the registers on the DAC.
Headphone output tested.
Other outputs and Capture not tested yet.
Note: The red LED does not come on, but sound is still OK.

Signed-off-by: James Courtier-Dutton <James@superbug.co.uk>