pinctrl: gemini: Implement clock skew/delay config

This enabled pin config on the Gemini driver and implements
pin skew/delay so that the ethernet pins clocking can be
properly configured.

Acked-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>