core: s/isEIP155/isHomestead/g (fix IntrinsicGas signature var name) (#20300)

* core: s/isEIP155/isEIP2/ (fix)

This signature variable name reflects a spec'd change
in gas cost for creating contracts as documented in EIP2 (Homestead HF).

https://github.com/ethereum/EIPs/blob/master/EIPS/eip-2.md#specification

* core: s/isEIP2/sIsHomestead/g

Use isHomestead since Homestead is what the caller
and rest of the code uses.

core/state_transition.go

@@ -76,10 +76,10 @@ type Message interface {
 }
 
 // IntrinsicGas computes the 'intrinsic gas' for a message with the given data.
-func IntrinsicGas(data []byte, contractCreation, isEIP155 bool, isEIP2028 bool) (uint64, error) {
+func IntrinsicGas(data []byte, contractCreation, isHomestead bool, isEIP2028 bool) (uint64, error) {
 	// Set the starting gas for the raw transaction
 	var gas uint64
-	if contractCreation && isEIP155 {
+	if contractCreation && isHomestead {
 		gas = params.TxGasContractCreation
 	} else {
 		gas = params.TxGas