tpm2_i2c_nuvoton: add irq validity check

In 570a3609 IRQ path is incorrectly always exercised while it should be
exercised only when there is an IRQ number allocated. This commit
reverts the old behavior.

[jarkko.sakkinen@linux.intel.com: updated description]

Fixes: 570a36097f3 ("tpm: drop 'irq' from struct tpm_vendor_specific")
Signed-off-by: Andrew Zamansky <andrew.zamansky@nuvoton.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

drivers/char/tpm/tpm_i2c_nuvoton.c

@@ -559,10 +559,8 @@ static int i2c_nuvoton_probe(struct i2c_client *client,
 	 *   TPM_INTF_INT_LEVEL_LOW | TPM_INTF_DATA_AVAIL_INT
 	 * The IRQ should be set in the i2c_board_info (which is done
 	 * automatically in of_i2c_register_devices, for device tree users */
-	chip->flags |= TPM_CHIP_FLAG_IRQ;
 	priv->irq = client->irq;
-
-	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
+	if (client->irq) {
 		dev_dbg(dev, "%s() priv->irq\n", __func__);
 		rc = devm_request_irq(dev, client->irq,
 				      i2c_nuvoton_int_handler,
@@ -572,9 +570,9 @@ static int i2c_nuvoton_probe(struct i2c_client *client,
 		if (rc) {
 			dev_err(dev, "%s() Unable to request irq: %d for use\n",
 				__func__, priv->irq);
-			chip->flags &= ~TPM_CHIP_FLAG_IRQ;
 			priv->irq = 0;
 		} else {
+			chip->flags |= TPM_CHIP_FLAG_IRQ;
 			/* Clear any pending interrupt */
 			i2c_nuvoton_ready(chip);
 			/* - wait for TPM_STS==0xA0 (stsValid, commandReady) */