extcon: arizona: Additional settings to improve accuracy of HP detect

If the TST_CAP_SEL bits aren't set correctly on wm5110/8280 there will
be a 100k load along side the headphones, which will affect the accurary
towards the very top of the detection range. This patch sets those bits.

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>