les: fix megacheck warnings (#14941)

* les: fix megacheck warnings

* les: fixed testGetProofs

les/server.go

@@ -44,7 +44,6 @@ type LesServer struct {
 	defParams       *flowcontrol.ServerParams
 	lesTopic        discv5.Topic
 	quitSync        chan struct{}
-	stopped         bool
 }
 
 func NewLesServer(eth *eth.Ethereum, config *eth.Config) (*LesServer, error) {
@@ -118,16 +117,6 @@ func (list RequestCostList) decode() requestCostTable {
 	return table
 }
 
-func (table requestCostTable) encode() RequestCostList {
-	list := make(RequestCostList, len(table))
-	for idx, code := range reqList {
-		list[idx].MsgCode = code
-		list[idx].BaseCost = table[code].baseCost
-		list[idx].ReqCost = table[code].reqCost
-	}
-	return list
-}
-
 type linReg struct {
 	sumX, sumY, sumXX, sumXY float64
 	cnt                      uint64