cnPilot APs should obtain time via NTP when option 42 is provided via DHCP

Regarding a ticket 207801.

Response from the engineering team:

Currently we are not acknowledging option 42 (NTP) from DHCP. 

show ip dhcp-client-info will show the NTP server IPs but this will not get into effect.

Please add possibility to obtain time vit NTP with DHCP option 42.