Mem: Use deque instead of list for bus retries

This patch changes the data structure used to keep track of ports that
should be told to retry. As the bus is doing this in an FCFS way,
there is no point having a list. A deque is a better match (and is at
least in theory a better choice from a performance point of view).

src/mem/bus.hh

@@ -51,7 +51,7 @@
 #ifndef __MEM_BUS_HH__
 #define __MEM_BUS_HH__
 
-#include <list>
+#include <deque>
 #include <set>
 
 #include "base/addr_range_map.hh"
@@ -213,7 +213,7 @@ class BaseBus : public MemObject
          * An array of ports that retry should be called
          * on because the original send failed for whatever reason.
          */
-        std::list<PortClass*> retryList;
+        std::deque<PortClass*> retryList;
 
         /**
          * Release the bus layer after being occupied and return to an