drivers/iommu/msm_iommu_dev.c: fix leak and clean up error paths

Fix two obvious problems:

1. We have registered msm_iommu_driver first, and need unregister it
when registered msm_iommu_ctx_driver fail

2. We don't need to kfree drvdata before kzalloc was successful.

[[e-mail]: remove now-unneeded initialization of ctx_drvdata, remove unneeded braces]
Signed-off-by: Libo Chen <[e-mail]>
Acked-by: David Brown <[e-mail]>
Cc: David Woodhouse <[e-mail]>
Cc: James Hogan <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/iommu/msm_iommu_dev.c

···
 {
 	struct msm_iommu_ctx_dev *c = pdev->dev.platform_data;
 	struct msm_iommu_drvdata *drvdata;
-	struct msm_iommu_ctx_drvdata *ctx_drvdata = NULL;
+	struct msm_iommu_ctx_drvdata *ctx_drvdata;
 	int i, ret;
-	if (!c || !pdev->dev.parent) {
-		ret = -EINVAL;
-		goto fail;
-	}
+
+	if (!c || !pdev->dev.parent)
+		return -EINVAL;
 
 	drvdata = dev_get_drvdata(pdev->dev.parent);
-
-	if (!drvdata) {
-		ret = -ENODEV;
-		goto fail;
-	}
+	if (!drvdata)
+		return -ENODEV;
 
 	ctx_drvdata = kzalloc(sizeof(*ctx_drvdata), GFP_KERNEL);
-	if (!ctx_drvdata) {
-		ret = -ENOMEM;
-		goto fail;
-	}
+	if (!ctx_drvdata)
+		return -ENOMEM;
+
 	ctx_drvdata->num = c->num;
 	ctx_drvdata->pdev = pdev;
 
···
 
 	ret = platform_driver_register(&msm_iommu_ctx_driver);
 	if (ret != 0) {
+		platform_driver_unregister(&msm_iommu_driver);
 		pr_err("Failed to register IOMMU context driver\n");
 		goto error;
 	}