nouveau/acpi: improve detection of what is IGD and what is DIS.

This improves the IGD/DIS picking using firstly if Intel, then
if the bus is bus 0. There may be a correct way to do this, but
I've no idea what it is.
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/nouveau/nouveau_acpi.c

@@ -130,9 +130,14 @@ static int nouveau_dsm_init(void)
 
 static int nouveau_dsm_get_client_id(struct pci_dev *pdev)
 {
-	if (nouveau_dsm_priv.dhandle == DEVICE_ACPI_HANDLE(&pdev->dev))
+	/* easy option one - intel vendor ID means Integrated */
+	if (pdev->vendor == PCI_VENDOR_ID_INTEL)
 		return VGA_SWITCHEROO_IGD;
-	else
+
+	/* is this device on Bus 0? - this may need improving */
+	if (pdev->bus->number == 0)
+		return VGA_SWITCHEROO_IGD;
+
 	return VGA_SWITCHEROO_DIS;
 }