drm/msm/a6xx: Rename gmu phandle to qcom,gmu

>From the review for the DT bindings for the GPU/GMU it
was suggested that the phandle for the GMU be
'qcom,gmu' instead of just 'gmu'.
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/adreno/a6xx_gpu.c

@@ -799,7 +799,7 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
 	}
 
 	/* Check if there is a GMU phandle and set it up */
-	node = of_parse_phandle(pdev->dev.of_node, "gmu", 0);
+	node = of_parse_phandle(pdev->dev.of_node, "qcom,gmu", 0);
 
 	/* FIXME: How do we gracefully handle this? */
 	BUG_ON(!node);