To use SNTP support, add define CONFIG_CMD_SNTP to theconfiguration file of the board.The "sntp" command gets network time from NTP time server andsyncronize RTC of the board. This command needs the command lineparameter of server's IP address or environment variable"ntpserverip". The network time is sent as UTC. So if you want toset local time to RTC, set the offset in second from UTC to theenviroment variable "time offset".If the DHCP server provides time server's IP or time offset, youdon't need to set the above environment variables yourself.Current limitations of SNTP support:1. The roundtrip time is ignored.2. Only the 1st NTP server IP, in the option ntp-servers of DHCP, will be used.