drm/nouveau: Use pci_get_base_class() to reduce duplicated code

Use pci_get_base_class() to reduce duplicated code. No functional change
intended.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Sui Jingfeng <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
Reviewed-by: Alex Deucher <[e-mail]>
Cc: Ben Skeggs <[e-mail]>
Cc: Karol Herbst <[e-mail]>
Cc: Lyude Paul <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>

drivers/gpu/drm/nouveau/nouveau_acpi.c

···
 		printk("MXM: GUID detected in BIOS\n");
 
 	/* now do DSM detection */
-	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL) {
-		vga_count++;
+	while ((pdev = pci_get_base_class(PCI_BASE_CLASS_DISPLAY, pdev))) {
+		if ((pdev->class != PCI_CLASS_DISPLAY_VGA << 8) &&
+		    (pdev->class != PCI_CLASS_DISPLAY_3D << 8))
+			continue;
 
-		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus,
-				      &has_optimus_flags, &has_power_resources);
-	}
-
-	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_3D << 8, pdev)) != NULL) {
 		vga_count++;
 
 		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus,