params: Convert the CPU objects to use the auto generated param structs.

A whole bunch of stuff has been converted to use the new params stuff, but
the CPU wasn't one of them.  While we're at it, make some things a bit
more stylish. Most of the work was done by Gabe, I just cleaned stuff up
a bit more at the end.

src/cpu/simple/SConscript

@@ -47,3 +47,4 @@ if 'AtomicSimpleCPU' in env['CPU_MODELS'] or \
 
 if need_simple_base:
     Source('base.cc')
+    SimObject('BaseSimpleCPU.py')