extcon: arizona: Remove duplicate set of input parent device

devm_input_allocate_device already sets the parent device to be that
passed to it, we also set this manually in arizona_extcon_probe. This
patch removes the redundant set from arizona_extcon_probe.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>