memory: tegra: Do not try to probe SMMU on Tegra20

Tegra20 doesn't have SMMU. Move out checking of the SMMU presence from
the SMMU driver into the Memory Controller driver. This change makes code
consistent in regards to how GART/SMMU presence checking is performed.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/tegra-smmu.c

@@ -982,10 +982,6 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev,
 	u32 value;
 	int err;
 
-	/* This can happen on Tegra20 which doesn't have an SMMU */
-	if (!soc)
-		return NULL;
-
 	smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
 	if (!smmu)
 		return ERR_PTR(-ENOMEM);

drivers/memory/tegra/mc.c

@@ -695,11 +695,13 @@ static int tegra_mc_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "failed to register reset controller: %d\n",
 			err);
 
-	if (IS_ENABLED(CONFIG_TEGRA_IOMMU_SMMU)) {
+	if (IS_ENABLED(CONFIG_TEGRA_IOMMU_SMMU) && mc->soc->smmu) {
 		mc->smmu = tegra_smmu_probe(&pdev->dev, mc->soc->smmu, mc);
-		if (IS_ERR(mc->smmu))
+		if (IS_ERR(mc->smmu)) {
 			dev_err(&pdev->dev, "failed to probe SMMU: %ld\n",
 				PTR_ERR(mc->smmu));
+			mc->smmu = NULL;
+		}
 	}
 
 	if (IS_ENABLED(CONFIG_TEGRA_IOMMU_GART) && !mc->soc->smmu) {