Fix userdata partition's ext4 mount point to data.

Bug: 3041475
Change-Id: I07306cd9c90072626dfc132d6655618ae70e64be
diff --git a/tools/releasetools/img_from_target_files b/tools/releasetools/img_from_target_files
index 871e295..f10af49 100755
--- a/tools/releasetools/img_from_target_files
+++ b/tools/releasetools/img_from_target_files
@@ -64,7 +64,7 @@
   if OPTIONS.info_dict["fstab"]["/data"].fs_type.startswith("ext"):
     build_command = ["mkuserimg.sh",
                      user_dir, img.name,
-                     OPTIONS.info_dict["fstab"]["/data"].fs_type, "userdata"]
+                     OPTIONS.info_dict["fstab"]["/data"].fs_type, "data"]
     if "userdata_size" in OPTIONS.info_dict:
       build_command.append(str(OPTIONS.info_dict["userdata_size"]))
   else: