ALSA: hda: cs35l41: Move external boost handling to lib for ASoC use

To add support for external boost for ASoC move the HDA external
boost implementation to the shared lib.

Signed-off-by: Lucas Tanure <tanureal@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20220413083728.10730-15-tanureal@opensource.cirrus.com


Signed-off-by: Takashi Iwai <tiwai@suse.de>