drm: sti: allow to change hdmi ddc i2c adapter

Depending of the board configuration i2c for ddc could change,
this patch allow to use a phandle to specify which i2c controller to use.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
diff --git a/drivers/gpu/drm/sti/sti_hdmi.h b/drivers/gpu/drm/sti/sti_hdmi.h
index 61bec65..d00a3e0 100644
--- a/drivers/gpu/drm/sti/sti_hdmi.h
+++ b/drivers/gpu/drm/sti/sti_hdmi.h
@@ -62,6 +62,7 @@
 	wait_queue_head_t wait_event;
 	bool event_received;
 	struct reset_control *reset;
+	struct i2c_adapter *ddc_adapt;
 };
 
 u32 hdmi_read(struct sti_hdmi *hdmi, int offset);