ASoC: Create a generic Pi Hat WM8804 driver

Reduce the amount of duplicated code by creating a generic driver for
Pi Hat digi cards using the WM8804 codec.

This replaces the
Allo DigiOne, Hifiberry Digi/Pro, JustBoom Digi and IQAudIO Digi
dedicate soundcard drivers with a generic driver.

There are no significant changes to the runtime behavior of the drivers
and end users should not have to change any configuration settings
after upgrading.

Minor changes
* Check the return value of snd_soc_component_update_bits
* Added some pr_debug tracing
* Various checkpatch tidyups
* Updated allodigi-one to use use 128FS at > 96 Khz. This appears to
  be an omission in the original driver code so followed the Hifiberry
  DAC driver approach.

ASoC: rpi-wm8804-soundcard: use modern dai_link style

Signed-off-by: Matthias Reichl <[email protected]>

rpi-wm8804-soundcard: drop PWRDN register writes

Since kernel 4.0 the PWRDN register bits are under DAPM
control from the wm8804 driver.

Drop code that modifies that register to avoid interfering
with DAPM.

Signed-off-by: Matthias Reichl <[email protected]>

rpi-wm8804-soundcard: configure wm8804 clocks only on rate change

This should avoid clicks when stopping and immediately afterwards
starting a stream with the same samplerate as before.

Signed-off-by: Matthias Reichl <[email protected]>

rpi-wm8804-soundcard: Fixed MCLKDIV for Allo Digione

The Allo Digione board wants a fixed MCLKDIV of 256.

See: #3296

Signed-off-by: Phil Elwell <[email protected]>