extcon: gpio: Fix code cleanup

This patch fixes following minor cleanup:
 - Order the include files in alphabetical order.
 - Fix description of state_off in extcon_gpio.h
 - Add a descrition for check_on_resume in extcon_gpio.h

Signed-off-by: George Cherian <george.cherian@ti.com>
[Modify the name/description of patch to keep standary codiyg style by Chanwoo Choi]
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>