ARM: nomadik: move last custom calls to pinctrl

The I2C pins were still set up using custom nmk_* calls, move
these to use the pinctrl mapping table instead. There was also
a remaining call to turn the Ethernet pin to GPIO, and this is
now done implicitly by the GPIO-to-pinctrl range translation
calls.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>