drm/ttm/radeon: add dma32 support.

This add support for using dma32 memory on gpus that really need it.

Currently IGPs are left without DMA32 but we might need to change
that unless we can fix rs690.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index e7662ba..3060ce1 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -624,6 +624,7 @@
 	bool				gpu_lockup;
 	bool				shutdown;
 	bool				suspend;
+	bool				need_dma32;
 };
 
 int radeon_device_init(struct radeon_device *rdev,