extcon: usbc-tusb320: add usb_role_switch support

The connector child node of the TUSB320 device might be linked with a
dual-role capable USB controller. Add driver support for detecting a
usb_role_switch and setting its state in the typec interrupt handler.
This follows similar practice in other drivers in the typec subsystem,
which this extcon driver can opt-in to.

Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>