arm64: Finalize realm VCPU after reset

In order to run a VCPU belonging to a realm, that VCPU must be in the
finalized state. Finalize the CPU after reset, since kvmtool won't be
touching the VCPU state afterwards.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>