extcon: max8997: Set default of ADC debounce time during initialization

This patch set default of ADC Debounce Time(25ms) during probe step.
Also, can possible change ADC Debounce Time according to H/W situation
by using max8997_set_adc_debounce_time()

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>