pinctrl/nomadik: db8540: split clkout group

The clkout group is split into groups clkout1 and clkout2
which allows pins cklkout1 and clkout2 to be muxed
separately.

Signed-off-by: Patrice Chotard <patrice.chotard@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>