enable verkle on cancun block: take 2 (#28)

* enable verkle on cancun block: take 2

* fix typo.  make unreachable line panic message more clear

cmd/geth/chaincmd.go

@@ -49,7 +49,6 @@ var (
 		ArgsUsage: "<genesisPath>",
 		Flags: []cli.Flag{
 			utils.DataDirFlag,
-			utils.VerkleFlag,
 		},
 		Category: "BLOCKCHAIN COMMANDS",
 		Description: `
@@ -206,10 +205,6 @@ func initGenesis(ctx *cli.Context) error {
 	stack, _ := makeConfigNode(ctx)
 	defer stack.Close()
 
-	if ctx.GlobalBool(utils.VerkleFlag.Name) {
-		genesis.Config.UseVerkle = true
-	}
-
 	for _, name := range []string{"chaindata", "lightchaindata"} {
 		chaindb, err := stack.OpenDatabase(name, 0, 0, "", false)
 		if err != nil {