mfd: da9063: Add register definitions for DA9063 driver

This patch adds register definitions for the DA9063 PMIC. They will be used
by the following DA9063 mfd core driver and functional module drivers.

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