KVM: MMU: unify tdp_mmu_map_set_spte_atomic and tdp_mmu_set_spte_atomic_no_dirty_log

tdp_mmu_map_set_spte_atomic is not taking care of dirty logging anymore,
the only difference that remains is that it takes a vCPU instead of
the struct kvm.  Merge the two functions.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>