KVM: x86/mmu: Fix braces in kvm_recover_nx_lpages

No functional change intended.

Fixes: 29cf0f50

 ("kvm: x86/mmu: NX largepage recovery for TDP MMU")
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210202185734.1680553-10-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>