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/SConscript

@@ -71,6 +71,7 @@ temp_cpu_list = env['CPU_MODELS'][:]
 
 if env['USE_CHECKER']:
     temp_cpu_list.append('CheckerCPU')
+    SimObject('CheckerCPU.py')
 
 # Generate header.
 def gen_cpu_exec_signatures(target, source, env):