extcon: adc-jack: Fix checking return value of request_any_context_irq

On failure, request_any_context_irq() returns a negative value.
On success, it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.

Also ensure adc_jack_probe() return 0 on success.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>