iommu/tegra: fix device leak on probe_device()

Make sure to drop the reference taken to the iommu platform device when
looking up its driver data during probe_device().

Note that commit 9826e393e4a8 ("iommu/tegra-smmu: Fix missing
put_device() call in tegra_smmu_find") fixed the leak in an error path,
but the reference is still leaking on success.

Fixes: 891846516317 ("memory: Add NVIDIA Tegra memory controller support")
Cc: [e-mail] # 3.19: 9826e393e4a8
Cc: Miaoqian Lin <[e-mail]>
Acked-by: Robin Murphy <[e-mail]>
Acked-by: Thierry Reding <[e-mail]>
Signed-off-by: Johan Hovold <[e-mail]>
Signed-off-by: Joerg Roedel <[e-mail]>

drivers/iommu/tegra-smmu.c

···
 		return NULL;
 
 	mc = platform_get_drvdata(pdev);
-	if (!mc) {
-		put_device(&pdev->dev);
+	put_device(&pdev->dev);
+	if (!mc)
 		return NULL;
-	}
 
 	return mc->smmu;
 }