USB: typec: fsusb302: Drop empty set_current_limit implementation

The set_current_limit tcpm_dev callback is optional and the tcpm core
will already log the passed in values, so there is no need to have an
empty implementation of this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>