mfd: arizona: Update DT binding to support INn_MODE init_data

This patch update DT binding to support INn_MODE init_data. Each
input signal path can be configurated either as a Analogue or
Digital using the INn_MODE registers.

Signed-off-by: Inha Song <ideal.song@samsung.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>