mfd: Core support for the WM8350 AudioPlus PMIC

The WM8350 is an integrated audio and power management subsystem
intended for use as the primary PMIC in mobile multimedia applications.
The WM8350 can be controlled via either I2C or SPI - the control
interface is provided by a separate module in order to allow greatest
flexibility in configuring the kernel.

This driver was originally written by Liam Girdwood and has since been
updated to current kernel APIs and split up for submission by me.  All
the heavy lifting here was done by Liam.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Samuel Ortiz <sameo@openedhand.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>