The pcDuino V3 Nano has a 3.5mm TRRS jack socket for audio, using the
CTIA standard pinout, connected to HPOUTL, HPOUTR, HPCOM/HPCOMFB and
MICIN1/VMIC (via appropriate RC networks) on the A20. The PH00 GPIO is
wired for headphone plug detection: it reads 0 when nothing's plugged
in, and 1 when a plug is inserted.

LINEINL/R and FMINL/R are not connected.
Signed-off-by: Adam Sampson <ats@offog.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>