extcon: gpio: Remove duplicate data from struct gpio_extcon_data

There are duplicate data between struct gpio_extcon_data and struct
gpio_extcon_platform_data. This patch removes them from struct gpio_extcon_data.
Instead, this patch add pdata field to struct gpio_extcon_data.

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