drm: kill drm_device->irq

Like the last patch but adds a macro to get at the irq value instead of
dereferencing pdev directly.  Should  make things easier for the BSD guys and
if we ever support non-PCI devices.

Signed-off-by:  Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/via/via_mm.c b/drivers/gpu/drm/via/via_mm.c
index e640949..f694cb5 100644
--- a/drivers/gpu/drm/via/via_mm.c
+++ b/drivers/gpu/drm/via/via_mm.c
@@ -93,8 +93,7 @@
 	/* Last context, perform cleanup */
 	if (dev->ctx_count == 1 && dev->dev_private) {
 		DRM_DEBUG("Last Context\n");
-		if (dev->irq)
-			drm_irq_uninstall(dev);
+		drm_irq_uninstall(dev);
 		via_cleanup_futex(dev_priv);
 		via_do_cleanup_map(dev);
 	}