Modify systemd_logind_find_info_ptr_by_devnum to take a start argument, so
that it can be used to find all occurences of a devnum in an InputInfo list,
rather then just the first.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>