wgengine/netstack: remove unnecessary map in UpdateNetstackIPs

Updates #cleanup

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

wgengine/netstack/netstack.go

@@ -347,17 +347,15 @@ func (ns *Impl) UpdateNetstackIPs(nm *netmap.NetworkMap) {
 	}
 	newIPs := make(map[netip.Prefix]bool)
 
-	isAddr := map[netip.Prefix]bool{}
 	if selfNode.Valid() {
 		for i := range selfNode.Addresses().LenIter() {
 			ipp := selfNode.Addresses().At(i)
-			isAddr[ipp] = true
 			newIPs[ipp] = true
 		}
+		if ns.ProcessSubnets {
 			for i := range selfNode.AllowedIPs().LenIter() {
 				ipp := selfNode.AllowedIPs().At(i)
-			if !isAddr[ipp] && ns.ProcessSubnets {
+				newIPs[ipp] = true
-				newIPs[ipPrefixToAddressWithPrefix(ipp)] = true
 			}
 		}
 	}