target-i386: Clear KVM CPUID features if KVM is disabled

This will ensure all checks for features[FEAT_KVM] in the code
will be correct in case the KVM CPUID leaf is completely
disabled.
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>

target-i386/cpu.c

@@ -3038,6 +3038,10 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp)
         cpu->env.features[w] &= ~minus_features[w];
     }
 
+    if (!kvm_enabled() || !cpu->expose_kvm) {
+        env->features[FEAT_KVM] = 0;
+    }
+
     x86_cpu_enable_xsave_components(cpu);
 
     /* CPUID[EAX=7,ECX=0].EBX always increased level automatically: */