Get VM from vCPU rather than passing it as well.
Get VM from vCPU rather than passing it as well.

Change-Id: If6f6b274a25c797f335c2d087742835565a0553a

project-oak/hafnium-verification,project-oak/hafnium-verification,project-oak/hafnium-verification,project-oak/hafnium-verification,project-oak/hafnium-verification,project-oak/hafnium-verification,project-oak/hafnium-verification