style: [patch 3/22] reduce include dependencies in some headers

Used cppclean to help identify useless includes and removed them. This
involved erroneously included headers, but also cases where forward
declarations could have been used rather than a full include.

src/sim/ticked_object.hh

@@ -48,9 +48,10 @@
 #ifndef __SIM_TICKED_OBJECT_HH__
 #define __SIM_TICKED_OBJECT_HH__
 
-#include "params/TickedObject.hh"
 #include "sim/clocked_object.hh"
 
+class TickedObjectParams;
+
 /** Ticked attaches gem5's event queue/scheduler to evaluate
  *  calls and provides a start/stop interface to ticking.
  *