drm: rework PCI/platform driver interface.

This abstracts the pci/platform interface out a step further,
we can go further but this is far enough for now to allow USB
to be plugged in.

The drivers now just call the init code directly for their
device type.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 3dadfa2..cb49685 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -74,23 +74,13 @@
 {
 	struct drm_irq_busid *p = data;
 
-	if (drm_core_check_feature(dev, DRIVER_USE_PLATFORM_DEVICE))
+	if (!dev->driver->bus->irq_by_busid)
 		return -EINVAL;
 
 	if (!drm_core_check_feature(dev, DRIVER_HAVE_IRQ))
 		return -EINVAL;
 
-	if ((p->busnum >> 8) != drm_get_pci_domain(dev) ||
-	    (p->busnum & 0xff) != dev->pdev->bus->number ||
-	    p->devnum != PCI_SLOT(dev->pdev->devfn) || p->funcnum != PCI_FUNC(dev->pdev->devfn))
-		return -EINVAL;
-
-	p->irq = dev->pdev->irq;
-
-	DRM_DEBUG("%d:%d:%d => IRQ %d\n", p->busnum, p->devnum, p->funcnum,
-		  p->irq);
-
-	return 0;
+	return dev->driver->bus->irq_by_busid(dev, p);
 }
 
 /*