KVM: Portability: Add vcpu and hardware management arch hooks

Add the following hooks:

  void decache_vcpus_on_cpu(int cpu);
  int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu);
  void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu);
  void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu);
  void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
  void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu);
  struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id);
  void kvm_arch_vcpu_destory(struct kvm_vcpu *vcpu);
  int kvm_arch_vcpu_reset(struct kvm_vcpu *vcpu);
  void kvm_arch_hardware_enable(void *garbage);
  void kvm_arch_hardware_disable(void *garbage);
  int kvm_arch_hardware_setup(void);
  void kvm_arch_hardware_unsetup(void);
  void kvm_arch_check_processor_compat(void *rtn);

Signed-off-by: Zhang Xiantao <xiantao.zhang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>