Generate extra userdata partition if needed

* To support variants of devices which may come in 16/32/64GB variants.

Change-Id: I74c32d8316f0450a1445fe95a95e5cabb7a9dd1b
(cherry picked from commit aae837f9cbcff739cb660016a6d1abd7ef4663db)
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 3b523a5..36f3305 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -612,8 +612,8 @@
   fs_type = None
   limit = None
   if info_dict["fstab"]:
-    if mount_point == "/userdata":
-      mount_point = "/data"
+    if mount_point == "/userdata_extra": mount_point = "/data"
+    if mount_point == "/userdata": mount_point = "/data"
     p = info_dict["fstab"][mount_point]
     fs_type = p.fs_type
     device = p.device