ARM: ux500: Add support for ab8500 regulators into the Device Tree

Here we supply the information required to setup regulators successfully
on Snowball and other db8500 variants which use the ab8500 regulators.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>