l2geth: fee too high error message

Update the error message returned when the fee is too
high to return the correct multiplication. It should be
the expected fee * the fee threshold up.

.changeset/nervous-donuts-laugh.md

+---
+'@eth-optimism/l2geth': patch
+---
+
+Return correct value in L2 Geth fee too high error message

l2geth/rollup/sync_service.go

@@ -880,7 +880,7 @@ func (s *SyncService) verifyFee(tx *types.Transaction) error {
 		}
 		if errors.Is(err, fees.ErrFeeTooHigh) {
 			return fmt.Errorf("%w: %d, use less than %d * %f", fees.ErrFeeTooHigh, userFee,
-				expectedFee, s.feeThresholdDown)
+				expectedFee, s.feeThresholdUp)
 		}
 		return err
 	}