4823 don't open-code NSEC2MSEC and MSEC2NSEC

@@ -235,13 +235,12 @@
 stop_init_reboot(dhcp_smach_t *dsmp, unsigned int n_requests)
 {
         if (dsmp->dsm_isv6) {
                 uint_t nowabs, maxabs;
 
-                nowabs = gethrtime() / (NANOSEC / MILLISEC);
-                maxabs = dsmp->dsm_neg_hrtime / (NANOSEC / MILLISEC) +
-                    DHCPV6_CNF_MAX_RD;
+                nowabs = NSEC2MSEC(gethrtime());
+                maxabs = NSEC2MSEC(dsmp->dsm_neg_hrtime) + DHCPV6_CNF_MAX_RD;
                 if (nowabs < maxabs) {
                         /* Cap the timer based on the maximum */
                         if (nowabs + dsmp->dsm_send_timeout > maxabs)
                                 dsmp->dsm_send_timeout = maxabs - nowabs;
                         return (B_FALSE);