ARM: ep93xx: move pinctrl interfaces into include/linux/soc

ARM: ep93xx: move pinctrl interfaces into include/linux/soc

ep93xx does not have a proper pinctrl driver, but does things
ad-hoc through mach/platform.h, which is also used for setting
up the boards.

To avoid using mach/*.h headers completely, let's move the interfaces
into include/linux/soc/. This is far from great, but gets the job
done here, without the need for a proper pinctrl driver.

Acked-by: Alexander Sverdlin <[email protected]>
Acked-by: H Hartley Sweeten <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Signed-off-by: Olof Johansson <[email protected]>