Enable pkvm based on the relevant sysprop rather than /dev/kvm

1. This is simpler, as it can be triggered by logic in the init.rc
2. The old method of probing /dev/kvm fails if non-protected kvm
   is enabled: the device will exist, but pkvm is not enable

Bug: 346525496
Test: observe that pkvm is enabled after double reboot
Change-Id: I2f557ed56f13458a288ede34e672692b511b6bc9
2 files changed