scons: Get rid of a redundant import of code_formatter.

This module was already imported at the top of the SConscript.

Change-Id: I1357beda2adcc085c122df15397c769694a73fab
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/48361
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>

src/SConscript

@@ -800,7 +800,6 @@ class DictImporter(object):
 
 import m5.SimObject
 import m5.params
-from m5.util import code_formatter
 
 m5.SimObject.clear()
 m5.params.clear()