ARM: sun7i: Add sunxi codec device node

The A20 SoC includes the Allwinner audio codec, capable of both 24-bit
playback and capture. This commit adds a device node for it.

Signed-off-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>