configs: update pht-pf-level default and enhance prefetcher configuration

[zephyrols]

Using act_entries=64 and pht_pf_level=2 provide a hyper performance than act_entries=32 and pht_pf_level=1 in solo L1 sms prefetcher. New Params solve the problem of negative optimization on omnetpp.

I also tried some other parameters, about (act_entries, pht_entries, pht_assoc, pht_pf_level). The results are as follows. From this, it can be observed that the common features of high-score configuration are a greater number of act entries and pht prefetching that spans multiple layers to the L2.

[XiangShanRobot]

[Generated by GEM5 Performance Robot] commit: c0fe729e6cf2fe65a33639220f92e539ff8170ff workflow: gem5 Ideal Performance Test

Ideal Performance

Overall Score

	PR	Master	Diff(%)
Score	19.70	19.57	+0.69 🟢

[XiangShanRobot]

[Generated by GEM5 Performance Robot] commit: c0fe729e6cf2fe65a33639220f92e539ff8170ff workflow: gem5 Ideal BTB Performance Test

Ideal BTB Performance

Overall Score

	PR	Master	Diff(%)
Score	19.45	19.32	+0.66 🟢

[XiangShanRobot]

[Generated by GEM5 Performance Robot] commit: c0fe729e6cf2fe65a33639220f92e539ff8170ff workflow: gem5 Performance Test

Standard Performance

Overall Score

	PR	Master	Diff(%)
Score	15.96	15.84	+0.78 🟢

[jensen-yan]

please give a brief reason of this PR, give desired performance stats if possible.