ALSA: hda: Adding support for CS35L56 on HDA

Merge series from Richard Fitzgerald <rf@opensource.cirrus.com>:

This set of patches adds support for using the CS35L56 boosted smart
amplifier on HDA systems. In these systems the CS35L56 audio is
routed through a HDA-to-I2S bridge codec.

This doesn't include the changes to the Realtek driver to actually hook
up the CS35L56 driver, because we don't yet have the QUIRK IDs to
associate it with. But we want to publish the driver now so that it is
available for bringing up hardware with the CS35L56.

The first 9 patches are moving code out of the ASoC driver and into the
shared library so that it can be shared with the HDA driver.

Patch #10 fixes missing #includes in the HDA headers so that the CS35L56
driver doesn't have to #include headers that it doesn't use.