DHCP server freed next free allocated id

This fix a bug when 1 freed id is re-allocated and it set next free id to point already active ones.

Change-Id: Ia3ab76f1800cbee41f8b82aea3fc7f455132c6dc

Author: Juha Heiskanen

source/libDHCPv6/libDHCPv6_server.c

@@ -75,7 +75,8 @@ static uint16_t libdhcpv6_get_next_freed_id(dhcpv6_gua_server_entry_s *serverInf
         if ((cur->allocatedID - last_allocated_id) == 2) {
             //one missing sequence between last and current
             if (last_allocated_id + 1 == serverInfo->firstFreedId) {
-                //Skip
+                //Skip Current freedID this will update after this call to new one
+                last_allocated_id = cur->allocatedID;
                 continue;
             }
         } else if (last_allocated_id + 1 == serverInfo->firstFreedId) {