KVM: x86: use the fast way to invalidate all pages

Replace kvm_mmu_zap_all by kvm_mmu_invalidate_zap_all_pages

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>