drm/msm/a6xx: Avoid a nullptr dereference when speedbin setting fails

Calling a6xx_destroy() before adreno_gpu_init() leads to a null pointer
dereference on:

msm_gpu_cleanup() : platform_set_drvdata(gpu->pdev, NULL);

as gpu->pdev is only assigned in:

a6xx_gpu_init()
|_ adreno_gpu_init
    |_ msm_gpu_init()

Instead of relying on handwavy null checks down the cleanup chain,
explicitly de-allocate the LLC data and free a6xx_gpu instead.

Fixes: 76efc245 ("drm/msm/gpu: Fix crash during system suspend after unbind")
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/588919/Signed-off-by: Rob Clark <robdclark@chromium.org>

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

@@ -3062,7 +3062,8 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
 
 	ret = a6xx_set_supported_hw(&pdev->dev, config->info);
 	if (ret) {
-		a6xx_destroy(&(a6xx_gpu->base.base));
+		a6xx_llc_slices_destroy(a6xx_gpu);
+		kfree(a6xx_gpu);
 		return ERR_PTR(ret);
 	}