Fix Port pointer initialization.
Fix Port pointer initialization.

src/mem/port.hh:
    Initialize peer port pointer to NULL.
    Move private data members together.

--HG--
extra : convert_revision : dab01f81f0934758891a6b6dc2ad5328149d164b

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