drm: kill DRIVER_REQUIRE_AGP

Only the two intel drivers need this and they can easily check for
working agp support in their driver ->load callbacks.

This is the only reason why agp initialization could fail, so allows
us to rip out a bit of error handling code in the next patch.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/i810/i810_dma.c

@@ -1193,6 +1193,10 @@ static int i810_flip_bufs(struct drm_device *dev, void *data,
 
 int i810_driver_load(struct drm_device *dev, unsigned long flags)
 {
+	/* Our userspace depends upon the agp mapping support. */
+	if (!dev->agp)
+		return -EINVAL;
+
 	pci_set_master(dev->pdev);
 
 	return 0;