binman: Add a test to catch use of the old 'pos' property

This property has been changed to 'offset'. To help downstream users who
might still be using 'pos', add a check that this is not used by mistake.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/entry.py b/tools/binman/entry.py
index 6ce5dbd..77cfab9 100644
--- a/tools/binman/entry.py
+++ b/tools/binman/entry.py
@@ -143,6 +143,8 @@
 
         This reads all the fields we recognise from the node, ready for use.
         """
+        if 'pos' in self._node.props:
+            self.Raise("Please use 'offset' instead of 'pos'")
         self.offset = fdt_util.GetInt(self._node, 'offset')
         self.size = fdt_util.GetInt(self._node, 'size')
         self.align = fdt_util.GetInt(self._node, 'align')