drm/msm: Fix IOMMU clean up path in case msm_iommu_new() fails

msm_iommu_new() can fail and this change makes sure that we
detect the failure and free the allocated domain before going
any further.

Signed-off-by: Stephane Viau <sviau@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 8f70d92..6b02ada 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -651,6 +651,14 @@
 	if (iommu) {
 		dev_info(drm->dev, "%s: using IOMMU\n", name);
 		gpu->mmu = msm_iommu_new(&pdev->dev, iommu);
+		if (IS_ERR(gpu->mmu)) {
+			ret = PTR_ERR(gpu->mmu);
+			dev_err(drm->dev, "failed to init iommu: %d\n", ret);
+			gpu->mmu = NULL;
+			iommu_domain_free(iommu);
+			goto fail;
+		}
+
 	} else {
 		dev_info(drm->dev, "%s: no IOMMU, fallback to VRAM carveout!\n", name);
 	}