x86/pci/probe_roms: Use to_pci_driver() instead of pci_dev->driver

Struct pci_driver contains a struct device_driver, so for PCI devices, it's
easy to convert a device_driver * to a pci_driver * with to_pci_driver().
The device_driver * is in struct device, so we don't need to also keep
track of the pci_driver * in struct pci_dev.

Replace pdev->driver with to_pci_driver().  This is a step toward removing
pci_dev->driver.

[bhelgaas: split to separate patch]
Link: https://lore.kernel.org/r/20211004125935.2300113-11-u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

arch/x86/kernel/probe_roms.c

@@ -80,7 +80,7 @@ static struct resource video_rom_resource = {
  */
 static bool match_id(struct pci_dev *pdev, unsigned short vendor, unsigned short device)
 {
-	struct pci_driver *drv = pdev->driver;
+	struct pci_driver *drv = to_pci_driver(pdev->dev.driver);
 	const struct pci_device_id *id;
 
 	if (pdev->vendor == vendor && pdev->device == device)