UPSTREAM: KVM: arm64: Dedupe vCPU power off helpers

vcpu_power_off() and kvm_psci_vcpu_off() are equivalent; rename the
former and replace all callsites to the latter.

No functional change intended.

Signed-off-by: Oliver Upton <oupton@google.com>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220504032446.4133305-3-oupton@google.com


(cherry picked from commit 1e579429)
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 233587962
Bug: 233588291
Change-Id: I36e60324a2ed12fb93dd1e20c7337f454ade7bf7