remove a no-op line in the code (#17760)

les/flowcontrol/control.go

@@ -82,7 +82,6 @@ func (peer *ClientNode) RequestProcessed(cost uint64) (bv, realCost uint64) {
 	time := mclock.Now()
 	peer.recalcBV(time)
 	peer.bufValue -= cost
-	peer.recalcBV(time)
 	rcValue, rcost := peer.cm.processed(peer.cmNode, time)
 	if rcValue < peer.params.BufLimit {
 		bv := peer.params.BufLimit - rcValue