pinctrl: sunxi: add Allwinner A100/A133 pinctrl description

pinctrl: sunxi: add Allwinner A100/A133 pinctrl description

The Allwinner A100 SoC has been around for a while, and has now seemingly
been replaced with its close sibling A133.

Add the required mapping between the pinmux group strings and their
respective mux value, as far as used by U-Boot proper. Linux has some
basic (clock and pinctrl) support for a while, so we can build on the
names already used there.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>