config: Remove unused mem_size in fs.py
config: Remove unused mem_size in fs.py

This patch removes a segment of dead code that is never used.

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