uio: uio_pci_generic: don't fail probe if pdev->irq equals to IRQ_NOTCONNECTED

Some devices use 255 as default value of Interrupt Line register, and this
maybe causes pdev->irq is set as IRQ_NOTCONNECTED in some scenarios. For
example, NVMe controller connects to Intel Volume Management Device (VMD).
In this situation, IRQ_NOTCONNECTED means INTx line is not connected, not
fault. If bind uio_pci_generic to these devices, uio frame will return
-ENOTCONN through request_irq.

This patch allows binding uio_pci_generic to device with dev->irq of
IRQ_NOTCONNECTED.

Acked-by: Kyungsan Kim <ks0204.kim@samsung.com>
Signed-off-by: Jie Li <jie6.li@samsung.com>
Link: https://lore.kernel.org/r/1612153559-17028-1-git-send-email-jie6.li@samsung.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/uio/uio_pci_generic.c

@@ -92,7 +92,7 @@ static int probe(struct pci_dev *pdev,
 	gdev->info.version = DRIVER_VERSION;
 	gdev->info.release = release;
 	gdev->pdev = pdev;
-	if (pdev->irq) {
+	if (pdev->irq && (pdev->irq != IRQ_NOTCONNECTED)) {
 		gdev->info.irq = pdev->irq;
 		gdev->info.irq_flags = IRQF_SHARED;
 		gdev->info.handler = irqhandler;