dhcpd: fix build warning
CC:  dhcpd.c
In function 'dhcpd_openlistener',
inlined from 'dhcpd_run.part.0' at dhcpd.c:1513:20:
dhcpd.c:1425:3: error: 'strncpy' specified bound 16 equals destination size [-Werror=stringop-truncation]
1425 |   strncpy(req.ifr_name, interface, IFNAMSIZ);
|   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
@@ -1422,7 +1422,7 @@ static inline int dhcpd_openlistener(FAR const char *interface)
/* Get the IP address of the selected device */
- strncpy(req.ifr_name, interface, IFNAMSIZ);
+ strlcpy(req.ifr_name, interface, IFNAMSIZ);
ret = ioctl(sockfd, SIOCGIFADDR, (unsigned long)&req);
if (ret < 0)
{
