ARM64: dts: amlogic: Enable pin controller on GXBB-based platforms

Update DTS and DTSI files to enable the pin controller. We also now
support the blinking blue LED on the Odroid-C2.

Signed-off-by: Carlo Caione <carlo@endlessm.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>