drm/radeon/r600: don't do interrupts

Interrupts are not supported yet.  This prevents
things like mesa from trying to use them.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon_state.c b/drivers/gpu/drm/radeon/radeon_state.c
index aad0c6f..38537d9 100644
--- a/drivers/gpu/drm/radeon/radeon_state.c
+++ b/drivers/gpu/drm/radeon/radeon_state.c
@@ -3034,7 +3034,10 @@
 		value = GET_SCRATCH(dev_priv, 2);
 		break;
 	case RADEON_PARAM_IRQ_NR:
-		value = drm_dev_to_irq(dev);
+		if ((dev_priv->flags & RADEON_FAMILY_MASK) >= CHIP_R600)
+			value = 0;
+		else
+			value = drm_dev_to_irq(dev);
 		break;
 	case RADEON_PARAM_GART_BASE:
 		value = dev_priv->gart_vm_start;