add updated Norm12 autotest

Author: Clark

nipype/interfaces/spm/tests/test_auto_Normalize12.py

@@ -31,6 +31,9 @@ def test_Normalize12_inputs():
     matlab_cmd=dict(),
     mfile=dict(usedefault=True,
     ),
+    out_prefix=dict(field='woptions.prefix',
+    usedefault=True,
+    ),
     paths=dict(),
     sampling_distance=dict(field='eoptions.samp',
     ),