edtlib: Improve _interrupt_parent() function

According to the following comment on github
https://github.com/zephyrproject-rtos/zephyr/pull/77900/files#r1750393745
edtlib implementation is partially correct and it is missing two things:

1. If an ancestor has an interrupt-controller or interrupt-map property,
   the walk must terminate.
2. If an interrupt-parent property is found, the linked node must be a
   valid interrupt controller or nexus.

This commit add these checks.

Signed-off-by: Ioannis Damigos <[email protected]>

Author: ydamigos

scripts/dts/python-devicetree/src/devicetree/edtlib.py

@@ -2904,8 +2904,14 @@ def _interrupt_parent(start_node: dtlib_Node) -> dtlib_Node:
 
     while node:
         if "interrupt-parent" in node.props:
-            return node.props["interrupt-parent"].to_node()
+            iparent = node.props["interrupt-parent"].to_node()
+            assert "interrupt-controller" in iparent.props or "interrupt-map" in iparent.props
+            return iparent
         node = node.parent
+        if node is None:
+            _err(f"{start_node!r} no interrupt parent found")
+        if ("interrupt-controller" in node.props) or ("interrupt-map" in node.props):
+            return node
 
     _err(f"{start_node!r} has an 'interrupts' property, but neither the node "
          f"nor any of its parents has an 'interrupt-parent' property")