ARM: dts: sun6i: sina31s: Enable internal audio codec

The SinA31s routes the SoC's LINEOUT pins to a line out jack, and MIC1
to a microphone jack, with MBIAS providing phantom power.

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