core/vm: fix comment grammar (#19923)

* core/vm:modify comment errors

* modify its back to it's

core/vm/contract.go

@@ -162,7 +162,7 @@ func (c *Contract) Address() common.Address {
 	return c.self.Address()
 }
 
-// Value returns the contracts value (sent to it from it's caller)
+// Value returns the contract's value (sent to it from it's caller)
 func (c *Contract) Value() *big.Int {
 	return c.value
 }

core/vm/evm.go

@@ -35,7 +35,7 @@ type (
 	CanTransferFunc func(StateDB, common.Address, *big.Int) bool
 	// TransferFunc is the signature of a transfer function
 	TransferFunc func(StateDB, common.Address, common.Address, *big.Int)
-	// GetHashFunc returns the nth block hash in the blockchain
+	// GetHashFunc returns the n'th block hash in the blockchain
 	// and is used by the BLOCKHASH EVM op code.
 	GetHashFunc func(uint64) common.Hash
 )