regulator: rn5t618: Add RN5T567 PMIC support

Extend the driver to support Ricoh RN5T567. Support the additional
DCDC and slightly different voltage range of LDORTC1.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>