extcon: arizona: Use extcon cable API with index of extcon cable instead of string

Use extcon cable API instead of state API as it is much more
idiomatic.

Signed-off-by: Nikesh Oswal <Nikesh.Oswal@wolfsonmicro.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
[Modify patch title by Chanwoo Choi]
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>