cros_bundle_firmware: factor out conversion from fdt name to fmap name

BUG=chromium:595715
BRANCH=none
TEST=none

Change-Id: Idc5f7aadfc512a4a232a5a1ebdc491e1649902ee
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://chromium-review.googlesource.com/397178
Commit-Ready: Patrick Georgi <pgeorgi@chromium.org>
Tested-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
diff --git a/host/lib/bundle_firmware.py b/host/lib/bundle_firmware.py
index 9fcc797..48c61d7 100644
--- a/host/lib/bundle_firmware.py
+++ b/host/lib/bundle_firmware.py
@@ -648,6 +648,9 @@
     """
     self._out.Notice(msg)
 
+  def _FdtNameToFmap(self, fdtstr):
+    return re.sub('-', '_', fdtstr).upper()
+
   def _FmapNameByPath(self, path):
     """ Take list of names to form node path. Return FMAP name.
 
@@ -663,7 +666,7 @@
       CmdError if path not found.
     """
     lbl = self.fdt.GetLabel(self.fdt.GetFlashNode(*path))
-    return re.sub('-', '_', lbl).upper()
+    return self._FdtNameToFmap(lbl)
 
   def _PrepareCbfs(self, pack, blob_name):
     """Create CBFS blob in rw-boot-{a,b} FMAP sections.