drivers: gpio: AXP192 GPIO driver

AXP192 is a small power management IC, that also
features 5 GPIOS.
Besides GPIO driver this commit also includes needed modifications
in axp192 regulator and mfd driver as LDOIO0 functioanlity
is multiplexed with GPIO0 pin.

Signed-off-by: Martin Kiepfer <mrmarteng@teleschirm.org>
11 files changed