Implement ->set_mode(), ->get_mode() and ->set_suspend_xx() hooks
for act8865 with unlocked expert registers.

Based on work done by Borris Brezillon on [1].
[1] https://www.spinics.net/lists/kernel/msg2942960.htmlSigned-off-by: Raag Jadav <raagjadav@gmail.com>
Link: https://lore.kernel.org/r/1565721176-8955-2-git-send-email-raagjadav@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>