ARM: ux500: Remove traces of the ios_handler from platform code

Now MMCI on/off functionality is using the regulator framework
from the MMCI driver, there is no need to keep the ios_handler
laying around, duplicating functionality. So we're removing it.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>