extcon: gpio: Remove the usage of extcon_set_state()

This patch removes the usage of extcon_set_state() because it uses
the bit masking to change the state of external connectors. The extcon framework
should handle the state by extcon_set_cable_state_() with extcon id.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>