KVM: x86/mmu_audit: Remove unused "level" of audit_spte_after_sync()

The "int level" parameter of audit_spte_after_sync() is not used,
so remove it. No functional change intended.

Signed-off-by: Jinrong Liang <cloudliang@tencent.com>
Message-Id: <20220125095909.38122-6-cloudliang@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>