ASoC: add support for the Freescale P1022 DS reference board

The Freescale P1022 is a dual-core e500-based SOC with multimedia capabilities,
specifically the same SSI audio controller on the MPC8610.  The P1022 DS
reference board includes a P1022 and a Wolfson Microelectronics WM8776
codec.

Signed-off-by: Timur Tabi <timur@freescale.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>