mem-cache: AMPM Prefetcher fails when restoring from a checkpoint

The preriodic event triggers an assertion due to an incorrect tick value to
schedule when restoring from a checkpoint.

Change-Id: I9454dd0c97d5a098f8a409886e63f7a7e990947c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17732
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

src/mem/cache/prefetch/access_map_pattern_matching.hh

@@ -180,6 +180,7 @@ class AccessMapPatternMatching : public ClockedObject
     AccessMapPatternMatching(const AccessMapPatternMatchingParams* p);
     ~AccessMapPatternMatching()
     {}
+    void startup() override;
     void calculatePrefetch(const BasePrefetcher::PrefetchInfo &pfi,
         std::vector<QueuedPrefetcher::AddrPriority> &addresses);
 };