pinctrl: gemini: Support drive strength setting

The Gemini pin controller can set drive strength for a few
select groups of pins (not individually). Implement this
for GMAC0 and 1 (ethernet ports), IDE and PCI.

Cc: devicetree@vger.kernel.org
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

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>

pinctrl: Add DT bindings for Cortina Gemini

The Cortina Gemini pin controller uses the standard pin control
bindings for muxing functions with groups so these bindings
should be entirely uncontroversial.

Cc: devicetree@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>