sim: Remove SimObject::setMemoryMode

Remove SimObject::setMemoryMode from the main SimObject class since it
is only valid for the System class. In addition to removing the method
from the C++ sources, this patch also removes getMemoryMode and
changeTiming from SimObject.py and updates the simulation code to call
the (get|set)MemoryMode method on the System object instead.

src/sim/sim_object.cc

@@ -163,12 +163,6 @@ SimObject::resume()
     state = Running;
 }
 
-void
-SimObject::setMemoryMode(Enums::MemoryMode new_mode)
-{
-    panic("setMemoryMode() should only be called on systems");
-}
-
 void
 SimObject::switchOut()
 {

src/sim/sim_object.hh

@@ -255,13 +255,6 @@ class SimObject : public EventManager, public Serializable
      */
     virtual void resume();
 
-    /**
-     * Change the memory mode the simulator operates in.
-     *
-     * @note Should only be implemented in the System object.
-     */
-    virtual void setMemoryMode(Enums::MemoryMode new_mode);
-
     /**
      * Prepare a CPU model to be switched out, invoked on active CPUs
      * that are about to be replaced.