ARM: dts: sun6i: hummingbird: Enable internal audio codec

The Hummingbird A31 has headset and line in audio jacks and an onboard
mic routed to the pins for the SoC's internal codec. The line out pins
are routed to an onboard speaker amp, whose output is available on a
pin header.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>