MEM: Simplify ports by removing EventManager

This patch removes the inheritance of EventManager from the ports and
moves all responsibility for event queues to the owner. Eventually the
event manager should be the interface block, which could either be the
structural owner or a subblock like a LSQ in the O3 CPU for example.

src/cpu/simple/timing.cc

@@ -862,7 +862,7 @@ TimingSimpleCPU::DcachePort::recvTiming(PacketPtr pkt)
                 // faster than a CPU we could get two responses before
                 // next_tick expires
                 if (!retryEvent.scheduled())
-                    schedule(retryEvent, next_tick);
+                    cpu->schedule(retryEvent, next_tick);
                 return false;
             }
         }