serial: 8250_lpss: Switch over to MSI interrupts

Some devices support MSI interrupts. Let's at least try to use them in
platforms that provide MSI capability.

While at that, remove the now duplicated code from qrp_serial_setup().
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Link: https://lore.kernel.org/r/20191001115825.795700-1-felipe.balbi@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_lpss.c

@@ -221,17 +221,6 @@ static void qrk_serial_exit_dma(struct lpss8250 *lpss) {}
 
 static int qrk_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
 {
-	struct pci_dev *pdev = to_pci_dev(port->dev);
-	int ret;
-
-	pci_set_master(pdev);
-
-	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
-	if (ret < 0)
-		return ret;
-
-	port->irq = pci_irq_vector(pdev, 0);
-
 	qrk_serial_setup_dma(lpss, port);
 	return 0;
 }
@@ -293,16 +282,22 @@ static int lpss8250_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (ret)
 		return ret;
 
+	pci_set_master(pdev);
+
 	lpss = devm_kzalloc(&pdev->dev, sizeof(*lpss), GFP_KERNEL);
 	if (!lpss)
 		return -ENOMEM;
 
+	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
+	if (ret < 0)
+		return ret;
+
 	lpss->board = (struct lpss8250_board *)id->driver_data;
 
 	memset(&uart, 0, sizeof(struct uart_8250_port));
 
 	uart.port.dev = &pdev->dev;
-	uart.port.irq = pdev->irq;
+	uart.port.irq = pci_irq_vector(pdev, 0);
 	uart.port.private_data = &lpss->data;
 	uart.port.type = PORT_16550A;
 	uart.port.iotype = UPIO_MEM;
@@ -337,6 +332,7 @@ static int lpss8250_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 err_exit:
 	if (lpss->board->exit)
 		lpss->board->exit(lpss);
+	pci_free_irq_vectors(pdev);
 	return ret;
 }
 
@@ -348,6 +344,7 @@ static void lpss8250_remove(struct pci_dev *pdev)
 
 	if (lpss->board->exit)
 		lpss->board->exit(lpss);
+	pci_free_irq_vectors(pdev);
 }
 
 static const struct lpss8250_board byt_board = {