cpu: Fix a bug in the O3 CPU introduced by the cache line patch

This patch fixes a bug in the O3 fetch stage that was introduced when
the cache line size was moved to the system. By mistake, the
initialisation and resetting of the fetch stage was merged and put in
the constructor. The resetting is now re-added where it should be.

src/cpu/o3/fetch_impl.hh

@@ -344,6 +344,11 @@ DefaultFetch<Impl>::resetStage()
 
     wroteToTimeBuffer = false;
     _status = Inactive;
+
+    for (ThreadID tid = 0; tid < numThreads; tid++) {
+        cacheDataPC[tid] = 0;
+        cacheDataValid[tid] = false;
+    }
 }
 
 template<class Impl>