sim: Add voltage() function to clocked_object
sim: Add voltage() function to clocked_object

Adding voltage function which returns the current voltage
for a given clocked object. It's handy for power models and
similar stuff that need to retrieve voltage. Function
frequency() is already there, so I see no reason for not having
this one too.

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