Pinctrl cleanup and reworks for 3.16
This serie of patch:
- Moves the Allwinner pinctrl driver to a folder of its own
- removes the sunxi-pinctrl-pins header, and split the driver into a core
one, with all the logic, and smaller drivers, one for each SoC, that
declare the pins, and will provide to the core the set of pins.
- And does a few cleanups here and there.