Implement MCLK configuration options, add 32bit support
WM8804 can run with PLL frequencies of 256xfs and 128xfs for
most sample rates. At 192kHz only 128xfs is supported. The
existing driver selects 128xfs automatically for some lower
samples rates. By using an additional mclk_div divider, it
is now possible to control the behaviour. This allows using
256xfs PLL frequency on all sample rates up to 96kHz. It
should allow lower jitter and better signal quality. The
behavior has to be controlled by the sound card driver,
because some sample frequency share the same setting. e.g.
192kHz and 96kHz use 24.576MHz master clock. The only
difference is the MCLK divider.

This also added support for 32bit data.
Add support for HiFiBerry Digi.
Driver is based on the patched WM8804 driver.
Added support for HiFiBerry Digi board
Board initalization by I2C
Added HiFiBerry Digi configuration option
It will be compiled as a module by default