extcon: Add driver for TI TUSB320

This patch adds an extcon driver for the TI TUSB320 USB Type-C device.
This can be used to detect whether the port is configured as a
downstream or upstream facing port.

Signed-off-by: Michael Auchter <michael.auchter@ni.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>