KVM: PPC: Move vcpu_load/vcpu_put down to each ioctl case in kvm_arch_vcpu_ioctl

Although we already have kvm_arch_vcpu_async_ioctl() which doesn't require
ioctl to load vcpu, the sync ioctl code need to be cleaned up when
CONFIG_HAVE_KVM_VCPU_ASYNC_IOCTL is not configured.

This patch moves vcpu_load/vcpu_put down to each ioctl switch case so that
each ioctl can decide to do vcpu_load/vcpu_put or not independently.

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