regulator: Add support for RICOH PMIC RC5T583 regulator

The RC5T583 PMIC from RICOH consists of 4 DCDC and 10
LDOs. This driver supports the control of different
regulator output through regulator interface.
This driver depends on MFD driver of RC5T583 and uses
mfd rc5t583 apis to communicate to device for accessing
different device's registers.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>