platform/chrome: cros-ec-typec: Cleanup use of check_features

cros_ec_check_features() now returns a boolean. Remove the double NOT
operator since it's not required anymore.

No functional changes are expected with this patch.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20210923200321.3623222-1-pmalani@chromium.org