gpio: moxart: Switch to using the FTGPIO010 driver

This just deletes the Moxa ART driver and replaces it with the
more versatile Faraday FTGPIO010 driver.

Make this default on for ARCH_GEMINI and ARCH_MOXART so we do
not get Kconfig glitches.

Tested-by: Jonas Jensen <jonas.jensen@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>