extcon: sm5502: Move sm5502.h header file to extcon directory

This patch move sm5502.h header file from 'include/linux/extcon' to
'driver/extcon' because sm5502.h is used for driver/extcon/extcon-sm5502.c.
and remove duplicate license description.

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