KVM: PPC: Remove load/put vcpu for KVM_GET/SET_ONE_REG ioctl

Since the vcpu mutex locking/unlock has been moved out of vcpu_load()
/vcpu_put(), KVM_GET_ONE_REG and KVM_SET_ONE_REG doesn't need to do
ioctl with loading vcpu anymore. This patch removes vcpu_load()/vcpu_put()
from KVM_GET_ONE_REG and KVM_SET_ONE_REG ioctl.

Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>