sunxi: gpio: Add "allwinner,sun8i-a33-pinctrl"

Add "allwinner,sun8i-a33-pinctrl", this is used by the latest upstream
linux sunxi dts files.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>