extcon: arizona: Add support for new ADC value mic detect

Newer devices give users the option to make the 3/4 pole jack
determination using a software comparison rather than a hardware one.
This patch adds support for this functionality.

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