regulator: ab8500: Another push to synchronise recent AB8500 developments

This patch ensures that many of the recent developments pertaining to
the AB8500 regulator device are propagated out into the public arena.
It aims to update some of the existing initialisation values in
accordance with internal ST-Ericsson code submissions. This single
patch was originally a collection of updates which have been squashed
together to aid with clarity.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>