Provide success return indication from console_configure_dhcpd

Recent commit https://github.com/pfsense/pfsense/commit/9ea554ee5cb25ea3bf5bb6bf7997c6c7379ce349 added testing of the return status of console_configure_dhcpd() - this let a user effectively abort from doing anything if they have answered "y" to prompt_for_enable_dhcp_server() and are being asked for the start and end of the range, and then decide they do not want to proceed.
However, even when they gave good answers, status 0 was being returned. This prevented changes ever being implemented.
Redmine: https://redmine.pfsense.org/issues/4080
The fix is to return 1 at the routine end, when all is good and the code should proceed.