mem: Ensure that InvalidateReq is not forwarded as ReadExReq
mem: Ensure that InvalidateReq is not forwarded as ReadExReq

This patch fixes an issue where an InvalidationReq only traversed one
level of the cache hierarchy, and was subsequently turned into a
ReadExReq due to it needing writable, and the command not being
checked for explicitly.

aclifton/cpeg853-gem5,KuroeKurose/gem5,Weil0ng/gem5,Weil0ng/gem5,qizenguf/MLC-STT,briancoutinho0905/2dsampling,powerjg/gem5-ci-test,rallylee/gem5,rallylee/gem5,HwisooSo/gemV-update,rjschof/gem5,TUD-OS/gem5-dtu,sobercoder/gem5,gedare/gem5,rjschof/gem5,powerjg/gem5-ci-test,TUD-OS/gem5-dtu,aclifton/cpeg853-gem5,HwisooSo/gemV-update,rallylee/gem5,gedare/gem5,gedare/gem5,rjschof/gem5,aclifton/cpeg853-gem5,rallylee/gem5,gem5/gem5,cancro7/gem5,aclifton/cpeg853-gem5,qizenguf/MLC-STT,powerjg/gem5-ci-test,aclifton/cpeg853-gem5,powerjg/gem5-ci-test,sobercoder/gem5,cancro7/gem5,HwisooSo/gemV-update,Weil0ng/gem5,qizenguf/MLC-STT,powerjg/gem5-ci-test,briancoutinho0905/2dsampling,gem5/gem5,cancro7/gem5,gedare/gem5,SanchayanMaity/gem5,HwisooSo/gemV-update,rallylee/gem5,TUD-OS/gem5-dtu,HwisooSo/gemV-update,aclifton/cpeg853-gem5,qizenguf/MLC-STT,qizenguf/MLC-STT,HwisooSo/gemV-update,sobercoder/gem5,powerjg/gem5-ci-test,KuroeKurose/gem5,Weil0ng/gem5,qizenguf/MLC-STT,rallylee/gem5,KuroeKurose/gem5,KuroeKurose/gem5,cancro7/gem5,Weil0ng/gem5,briancoutinho0905/2dsampling,briancoutinho0905/2dsampling,rjschof/gem5,briancoutinho0905/2dsampling,SanchayanMaity/gem5,gem5/gem5,powerjg/gem5-ci-test,rjschof/gem5,KuroeKurose/gem5,rallylee/gem5,sobercoder/gem5,TUD-OS/gem5-dtu,SanchayanMaity/gem5,briancoutinho0905/2dsampling,gem5/gem5,gedare/gem5,qizenguf/MLC-STT,KuroeKurose/gem5,HwisooSo/gemV-update,rjschof/gem5,cancro7/gem5,gem5/gem5,gedare/gem5,cancro7/gem5,sobercoder/gem5,Weil0ng/gem5,aclifton/cpeg853-gem5,gedare/gem5,SanchayanMaity/gem5,Weil0ng/gem5,SanchayanMaity/gem5,gem5/gem5,TUD-OS/gem5-dtu,sobercoder/gem5,SanchayanMaity/gem5,rjschof/gem5,TUD-OS/gem5-dtu,cancro7/gem5,briancoutinho0905/2dsampling,gem5/gem5,sobercoder/gem5,TUD-OS/gem5-dtu,SanchayanMaity/gem5,KuroeKurose/gem5