dt-bindings: extcon: usbc-cros-ec: convert extcon-usbc-cros-ec.txt to yaml format

convert the binding file extcon-usbc-cros-ec.txt to
yaml format extcon-usbc-cros-ec.yaml

This was tested and verified on ARM with:
make dt_binding_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/extcon/extcon-usbc-cros-ec.yaml
make dtbs_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/extcon/extcon-usbc-cros-ec.yaml

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>