extcon: arizona: Add support for headphone detection on wm5110 rev D

wm5110 rev D is the first chip to use headphone detection IP 2, specify
such and make a small correction as the impedance value is actually read
in 0.5 ohm increments now.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>