Add new text for USB type C host.

If you use USB type C, you can charge Android from USB power or you can
supply power from Android to the other connected device.

Previously Android showed the notification saying "USB for charging".
The CL updates the text so that it shows the current power direction
explicitly.

Change-Id: Ic15ba70eaf8ade028283d8f490ac36e8d5e4db21
FIXED: 27706939