configs: Fix CPUClass typo in se.py

configs: Fix CPUClass typo in se.py

Change 719eb033fe435133abf15501c249eec10d1c861f added a typo
to se.py that breaks simpoint simulation, which generates the
following error:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/daniel/gem5/src/python/m5/main.py", line 435, in main
    exec filecode in scope
  File "./configs/example/se.py", line 217, in <module>
    if not CpuConfig.is_atomic_cpu(TestCPUClass):
NameError: name 'TestCPUClass' is not defined

Change-Id: Ideede8c96a40ee16af733c3d57b02b64f1a18d12
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/13267
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>