extcon: Add new EXTCON_CHG_WPT for Wireless Power Transfer device

This patchs add the new EXTCON_CHG_WPT for Wireless Power Transfer[1].
The Wireless Power Transfer is the transmission of electronical energy
from a power source. The EXTCON_CHG_WPT has the EXTCON_TYPE_CHG.

[1] https://en.wikipedia.org/wiki/Wireless_power_transfer



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