extcon: usbc-tusb320: add USB_ROLE_SWITCH dependency

When CONFIG_USB_ROLE_SWITCH=m, tusb320 cannot be built-in:

ld.lld: error: undefined symbol: fwnode_usb_role_switch_get
>>> referenced by extcon-usbc-tusb320.c
>>> drivers/extcon/extcon-usbc-tusb320.o:(tusb320_probe) in archive vmlinux.a
ld.lld: error: undefined symbol: usb_role_switch_set_role
>>> referenced by extcon-usbc-tusb320.c
>>> drivers/extcon/extcon-usbc-tusb320.o:(tusb320_state_update_handler) in archive vmlinux.a

Add the appropriate Kconfig dependency to prevent this
configuration but still allow the driver to be built-in
when USB_ROLE_SWITCH is disabled.

Fixes: df101446a402 ("extcon: usbc-tusb320: add usb_role_switch support")
Signed-off-by: Arnd Bergmann <[e-mail]>
Reviewed-by: Alvin Šipraga <[e-mail]>
Signed-off-by: Chanwoo Choi <[e-mail]>

drivers/extcon/Kconfig

···
 	tristate "TI TUSB320 USB-C extcon support"
 	depends on I2C && TYPEC
 	select REGMAP_I2C
+	depends on USB_ROLE_SWITCH || !USB_ROLE_SWITCH
 	help
 	  Say Y here to enable support for USB Type C cable detection extcon
 	  support using a TUSB320.