Fix for bug 3952

Made makedhcp be able to handle the case where site.nameservers or
networks.nameservers is a comma delimited list with <xcatmaster>
keyword in it.

xCAT-server/lib/xcat/plugins/dhcp.pm

@@ -2176,10 +2176,7 @@ sub addnet
             }
 
             # convert <xcatmaster> to nameserver IP
-            if ($nameservers eq '<xcatmaster>')
-            {
-                $nameservers = $myip;
-            }
+            $nameservers =~ s/<xcatmaster>/$myip/g;
 
             if (!$ntpservers || ($ntpservers eq '<xcatmaster>'))
             {