mach-ux500: voltage domain regulators for DB8500

The DB8500 has ePOD:s (electronic power domains) which are possible
to switch on/off to deactivate silicon blocks on the DB8500 SoC
by cutting their power without retention. We model these as simple
regulators with one bit on/off settings.

Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Bengt Jonsson <bengt.g.jonsson@stericsson.com>
Signed-off-by: Sundar Iyer <sundar.iyer@stericsson.com>
Signed-off-by: Jonas Aberg <jonas.aberg@stericsson.com>
Signed-off-by: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
Signed-off-by: Martin Persson <martin.persson@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>