TI TPS6594 PMIC support (RTC, pinctrl, regulators)

Merge series from Esteban Blanc <eblanc@baylibre.com>:

TPS6594 is a Power Management IC which provides regulators and others
features like GPIOs, RTC, watchdog, ESMs (Error Signal Monitor), and
PFSM (Pre-configurable Finite State Machine). The SoC and the PMIC can
communicate through the I2C or SPI interfaces.
TPS6594 is the super-set device while TPS6593 and LP8764 are derivatives.

This series adds support to TI TPS6594 PMIC and its derivatives.