drm: atmel-hlcdc: route DMA accesses through AHB interfaces

In relation with the actuall bandwidth consumed on a DMA Source interface,
choose the less used one for a created plane.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Nicolas Ferre <nicolas.ferre@atmel.com>
diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
index 93d0281..7a47f8c 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h
@@ -163,6 +163,7 @@
 atmel_hlcdc_create_planes(struct drm_device *dev);
 
 int atmel_hlcdc_plane_prepare_disc_area(struct drm_crtc_state *c_state);
+int atmel_hlcdc_plane_prepare_ahb_routing(struct drm_crtc_state *c_state);
 
 void atmel_hlcdc_crtc_irq(struct drm_crtc *c);