cmd/rlpdump: allow hex input to have leading '0x'

cmd/rlpdump/main.go

@@ -51,7 +51,7 @@ func main() {
 	var r io.Reader
 	switch {
 	case *hexMode != "":
-		data, err := hex.DecodeString(*hexMode)
+		data, err := hex.DecodeString(strings.TrimPrefix(*hexMode, "0x"))
 		if err != nil {
 			die(err)
 		}