drm/msm/a5xx: really check for A510 in a5xx_gpu_init

The commit 010c8bba ("drm: msm: adreno: Disable preemption on Adreno
510") added special handling for a510 (this SKU doesn't seem to support
preemption, so the driver should clamp nr_rings to 1). However the
gpu->revn is not yet set (it is set later, in adreno_gpu_init()) and
thus the condition is always false. Check config->rev instead.

Fixes: 010c8bba ("drm: msm: adreno: Disable preemption on Adreno 510")
Reported-by: Adam Skladowski <a39.skl@gmail.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Tested-by: Adam Skladowski <a39.skl@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/531511/Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/adreno/a5xx_gpu.c

@@ -1743,6 +1743,7 @@ struct msm_gpu *a5xx_gpu_init(struct drm_device *dev)
 {
 	struct msm_drm_private *priv = dev->dev_private;
 	struct platform_device *pdev = priv->gpu_pdev;
+	struct adreno_platform_config *config = pdev->dev.platform_data;
 	struct a5xx_gpu *a5xx_gpu = NULL;
 	struct adreno_gpu *adreno_gpu;
 	struct msm_gpu *gpu;
@@ -1769,7 +1770,7 @@ struct msm_gpu *a5xx_gpu_init(struct drm_device *dev)
 
 	nr_rings = 4;
 
-	if (adreno_is_a510(adreno_gpu))
+	if (adreno_cmp_rev(ADRENO_REV(5, 1, 0, ANY_ID), config->rev))
 		nr_rings = 1;
 
 	ret = adreno_gpu_init(dev, pdev, adreno_gpu, &funcs, nr_rings);