mfd: Initial support for the WM5110

The WM5110 is a highly-integrated low-power audio system for smartphones,
tablets and other portable audio devices. It combines an advanced DSP
feature set with a flexible, high-performance audio hub CODEC.

The support is based on the Arizona core driver.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>