regulator: da9063: Add Dialog DA9063 voltage regulators support.

The driver adds support for the following DA9063 PMIC regulators:
 - 11x LDOs (named LDO1 - LDO11),
 - 6x buck converters (BCORE1, BCORE2, BPRO, BMEM, BIO, BPERI),

Regulators provide following operations:
 - REGULATOR_CHANGE_STATUS and REGULATOR_CHANGE_VOLTAGE for all regulators,
 - REGULATOR_CHANGE_MODE for LDOs and buck converters, where:
     - LDOs allow REGULATOR_MODE_NORMAL and REGULATOR_MODE_STANDBY,
     - buck converters allow REGULATOR_MODE_FAST, REGULATOR_MODE_NORMAL
       and REGULATOR_MODE_STANDBY,
 - REGULATOR_CHANGE_CURRENT for buck converters (current limits).

The driver generates REGULATOR_EVENT_OVER_CURRENT for LDO3, LDO4, LDO7, LDO8
and LDO11.

Internally, PMIC provides two voltage configurations for normal and suspend
system state for each regulator. The driver switches between those on
suspend/wake-up to provide quick and fluent output voltage change.

This driver requires MFD core driver for operation.

Signed-off-by: Krystian Garbaciak <krystian.garbaciak@diasemi.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Mark Brown <broonie@linaro.org>