pinctrl: amlogic: gxbb: add UART_AO_B, I2C

Add pins for some more AO domain devices: UART_AO_B and I2C master &
slave.

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