dm: power: Convert as3722 to driver model

Convert this PMIC driver to driver model and fix up other users. The
regulator and GPIO functions are now handled by separate drivers.

Update nyan-big to work correct. Three boards will need to be updated by
the maintainers: apalis-tk1, cei-tk1-som. Also the TODO in the code re
as3722_sd_set_voltage() needs to be completed.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Tested-on: Jetson-TK1
Tested-by: Stephen Warren <swarren@nvidia.com>