iommu/virtio: Remove unused variable

Remove the variable of return. Issue found by
coccicheck(scripts/coccinelle/misc/returnvar.cocci)
Signed-off-by: Cristiane Naves <cristianenavescardoso09@gmail.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/virtio-iommu.c

@@ -153,7 +153,6 @@ static off_t viommu_get_write_desc_offset(struct viommu_dev *viommu,
  */
 static int __viommu_sync_req(struct viommu_dev *viommu)
 {
-	int ret = 0;
 	unsigned int len;
 	size_t write_len;
 	struct viommu_request *req;
@@ -182,7 +181,7 @@ static int __viommu_sync_req(struct viommu_dev *viommu)
 		kfree(req);
 	}
 
-	return ret;
+	return 0;
 }
 
 static int viommu_sync_req(struct viommu_dev *viommu)