mem: Add requests for DCache and Icache dual issuance.

[Ergou-ren]

Change-Id: I693f1f328805b65c9c5de36e0f783e1a9c0afbd6

1. Add parameters to control how many requests each layer can send per cycle.
2. Modify the periodic emission number of the layer corresponding to DCache and ICache. (1 => 2)

[XiangShanRobot]

[Generated by GEM5 Performance Robot]
commit: 776e376
workflow: gem5 Performance Test

Standard Performance

Overall Score

	PR	Master	Diff(%)
Score	16.23	16.20	+0.21 🟢

[XiangShanRobot]

[Generated by GEM5 Performance Robot]
commit: 776e376
workflow: gem5 Ideal BTB Performance Test

Ideal BTB Performance

Overall Score

	PR	Master	Diff(%)
Score	20.12	19.91	+1.05 🟢

[XiangShanRobot]

[Generated by GEM5 Performance Robot]
commit: 776e376
workflow: gem5 Ideal BTB Performance Test (no SC)

Ideal BTB Performance

Overall Score

	PR	Master	Diff(%)
Score	19.76	19.49	+1.40 🟢

[XiangShanRobot]

[Generated by GEM5 Performance Robot]
commit: 8538c1c
workflow: gem5 Performance Test

Standard Performance

Overall Score

	PR	Master	Diff(%)
Score	16.23	16.20	+0.21 🟢

[XiangShanRobot]

[Generated by GEM5 Performance Robot]
commit: 8538c1c
workflow: gem5 Ideal BTB Performance Test

Ideal BTB Performance

Overall Score

	PR	Master	Diff(%)
Score	20.16	19.91	+1.26 🟢

[XiangShanRobot]

[Generated by GEM5 Performance Robot]
commit: 8538c1c
workflow: gem5 Ideal BTB Performance Test (no SC)

Ideal BTB Performance

Overall Score

	PR	Master	Diff(%)
Score	19.81	19.54	+1.34 🟢