Fix mustpass generation

In 303f5900b4 we started emitting this element, but the generator was
slightly bogus.

Test: build mustpass

Change-Id: I2cf36637ba3264e1c254407d8f49f8c96b9d0cac
diff --git a/scripts/mustpass.py b/scripts/mustpass.py
index 32a6ed9..34e11f1 100644
--- a/scripts/mustpass.py
+++ b/scripts/mustpass.py
@@ -306,7 +306,7 @@
 	configElement = ElementTree.Element("configuration")
 
 	# add in metadata option for component name
-	ElementTree.subElement(configElement, "option", name="test-suite-tag", value="cts")
+	ElementTree.SubElement(configElement, "option", name="test-suite-tag", value="cts")
 	ElementTree.SubElement(configElement, "option", name="config-descriptor:metadata", key="component", value="deqp")
 
 	for package in mustpass.packages: