KVM x86/mmu changes for 6.5:

 - Add back a comment about the subtle side effect of try_cmpxchg64() in
   tdp_mmu_set_spte_atomic()

 - Add an assertion in __kvm_mmu_invalidate_addr() to verify that the target
   KVM MMU is the current MMU

 - Add a "never" option to effectively avoid creating NX hugepage recovery
   threads