platform/chrome: cros_ec_debugfs: Add PD port info to debugfs

Add info useful for debugging USB-PD port state.

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Benson Leung <bleung@chromium.org>