mem: Add check if SimpleDRAM nextReqEvent is scheduled
mem: Add check if SimpleDRAM nextReqEvent is scheduled

This check covers a case where a retry is called from the SimpleDRAM
causing a new request to appear before the DRAM itself schedules a
nextReqEvent. By adding this check, the event is not scheduled twice.

rallylee/gem5,TUD-OS/gem5-dtu,cancro7/gem5,yb-kim/gemV,rallylee/gem5,austinharris/gem5-riscv,KuroeKurose/gem5,joerocklin/gem5,powerjg/gem5-ci-test,aclifton/cpeg853-gem5,cancro7/gem5,gedare/gem5,cancro7/gem5,aclifton/cpeg853-gem5,briancoutinho0905/2dsampling,rallylee/gem5,aclifton/cpeg853-gem5,sobercoder/gem5,gem5/gem5,Weil0ng/gem5,zlfben/gem5,TUD-OS/gem5-dtu,yb-kim/gemV,austinharris/gem5-riscv,qizenguf/MLC-STT,zlfben/gem5,joerocklin/gem5,sobercoder/gem5,gedare/gem5,qizenguf/MLC-STT,joerocklin/gem5,SanchayanMaity/gem5,yb-kim/gemV,gem5/gem5,markoshorro/gem5,Weil0ng/gem5,kaiyuanl/gem5,gem5/gem5,rallylee/gem5,kaiyuanl/gem5,gedare/gem5,aclifton/cpeg853-gem5,zlfben/gem5,briancoutinho0905/2dsampling,qizenguf/MLC-STT,rjschof/gem5,TUD-OS/gem5-dtu,Weil0ng/gem5,samueldotj/TeeRISC-Simulator,yb-kim/gemV,gedare/gem5,KuroeKurose/gem5,sobercoder/gem5,kaiyuanl/gem5,powerjg/gem5-ci-test,briancoutinho0905/2dsampling,samueldotj/TeeRISC-Simulator,joerocklin/gem5,joerocklin/gem5,kaiyuanl/gem5,SanchayanMaity/gem5,rallylee/gem5,rjschof/gem5,yb-kim/gemV,gem5/gem5,rjschof/gem5,sobercoder/gem5,gem5/gem5,aclifton/cpeg853-gem5,zlfben/gem5,aclifton/cpeg853-gem5,cancro7/gem5,austinharris/gem5-riscv,KuroeKurose/gem5,yb-kim/gemV,samueldotj/TeeRISC-Simulator,sobercoder/gem5,Weil0ng/gem5,Weil0ng/gem5,cancro7/gem5,joerocklin/gem5,rjschof/gem5,HwisooSo/gemV-update,TUD-OS/gem5-dtu,KuroeKurose/gem5,gem5/gem5,markoshorro/gem5,qizenguf/MLC-STT,markoshorro/gem5,markoshorro/gem5,gem5/gem5,HwisooSo/gemV-update,yb-kim/gemV,kaiyuanl/gem5,Weil0ng/gem5,samueldotj/TeeRISC-Simulator,qizenguf/MLC-STT,HwisooSo/gemV-update,samueldotj/TeeRISC-Simulator,markoshorro/gem5,SanchayanMaity/gem5,briancoutinho0905/2dsampling,powerjg/gem5-ci-test,briancoutinho0905/2dsampling,Weil0ng/gem5,gedare/gem5,aclifton/cpeg853-gem5,rallylee/gem5,joerocklin/gem5,KuroeKurose/gem5,SanchayanMaity/gem5,austinharris/gem5-riscv,KuroeKurose/gem5,qizenguf/MLC-STT,powerjg/gem5-ci-test,markoshorro/gem5,joerocklin/gem5,austinharris/gem5-riscv,kaiyuanl/gem5,SanchayanMaity/gem5,briancoutinho0905/2dsampling,powerjg/gem5-ci-test,HwisooSo/gemV-update,powerjg/gem5-ci-test,cancro7/gem5,HwisooSo/gemV-update,powerjg/gem5-ci-test,TUD-OS/gem5-dtu,sobercoder/gem5,samueldotj/TeeRISC-Simulator,kaiyuanl/gem5,samueldotj/TeeRISC-Simulator,markoshorro/gem5,rjschof/gem5,rjschof/gem5,austinharris/gem5-riscv,austinharris/gem5-riscv,gedare/gem5,qizenguf/MLC-STT,briancoutinho0905/2dsampling,cancro7/gem5,TUD-OS/gem5-dtu,rallylee/gem5,HwisooSo/gemV-update,HwisooSo/gemV-update,KuroeKurose/gem5,rjschof/gem5,zlfben/gem5,zlfben/gem5,zlfben/gem5,gedare/gem5,SanchayanMaity/gem5,TUD-OS/gem5-dtu,SanchayanMaity/gem5,yb-kim/gemV,sobercoder/gem5