net/dns: [win] fix regression in disableDynamicUpdate

Somehow I accidentally set the wrong registry value here.
It should be DisableDynamicUpdate=1 and not EnableDNSUpdate=0.

This is a regression from 545639e.

Signed-off-by: Maisem Ali <maisem@tailscale.com>

net/dns/manager_windows.go

@@ -388,10 +388,10 @@ func (m windowsManager) Close() error {
 // Windows DHCP client from sending dynamic DNS updates for our interface to
 // AD domain controllers.
 func (m windowsManager) disableDynamicUpdates() error {
-	if err := m.setSingleDWORD(winutil.IPv4TCPIPInterfacePrefix, "EnableDNSUpdate", 0); err != nil {
+	if err := m.setSingleDWORD(winutil.IPv4TCPIPInterfacePrefix, "DisableDynamicUpdate", 1); err != nil {
 		return err
 	}
-	if err := m.setSingleDWORD(winutil.IPv6TCPIPInterfacePrefix, "EnableDNSUpdate", 0); err != nil {
+	if err := m.setSingleDWORD(winutil.IPv6TCPIPInterfacePrefix, "DisableDynamicUpdate", 1); err != nil {
 		return err
 	}
 	return nil