Fold kvm_mmu_unprotect_page() into kvm_mmu_unprotect_gfn_and_retry() now
that all other direct usage is gone.

No functional change intended.

Link: https://lore.kernel.org/r/20240831001538.336683-21-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>