KVM: PPC: Remove unused kvm_unmap_hva callback

Since commit fb1522e099 ("KVM: update to new mmu_notifier semantic
v2", 2017-08-31), the MMU notifier code in KVM no longer calls the
kvm_unmap_hva callback.  This removes the PPC implementations of
kvm_unmap_hva().

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

arch/powerpc/include/asm/kvm_ppc.h

@@ -295,7 +295,6 @@ struct kvmppc_ops {
 				     const struct kvm_userspace_memory_region *mem,
 				     const struct kvm_memory_slot *old,
 				     const struct kvm_memory_slot *new);
-	int (*unmap_hva)(struct kvm *kvm, unsigned long hva);
 	int (*unmap_hva_range)(struct kvm *kvm, unsigned long start,
 			   unsigned long end);
 	int (*age_hva)(struct kvm *kvm, unsigned long start, unsigned long end);