extcon: max77843: Clear IRQ bits state before request IRQ

IRQ signal before driver probe is needless because driver sends
current state after platform booting done.
So, this patch clears MUIC IRQ bits before request IRQ.

Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>