sw:vec: Disable WMMU in single-core test_runner script

Change-Id: I7c1e80dae014fad56ec31775e8ffb86b76e4e956
diff --git a/scripts/test_runner.py b/scripts/test_runner.py
index afb22c2..d65960a 100755
--- a/scripts/test_runner.py
+++ b/scripts/test_runner.py
@@ -95,6 +95,7 @@
 sysbus.cpu2 EnableExecutionTracing @%(trace_file)s PCAndOpcode """
 
         renode_script += """
+sysbus.cpu2 EnableExternalWindowMmu false
 start
 sysbus.vec_controlblock WriteDoubleWord 0xc 0"""
         self.script_params = {