regulator: Add a subdriver for TI TPS6105x regulator portions v2

This adds a subdriver for the regulator found inside the TPS61050
and TPS61052 chips.

Cc: Samuel Ortiz <samuel.ortiz@intel.com>
Cc: Ola Lilja <ola.o.lilja@stericsson.com>
Cc: Jonas Aberg <jonas.aberg@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>