qemu: hotplug: Fix TLS setup on disk hotplug

We need to check if TLS is enabled as the variable is a tristate.
Currently we'd setup TLS even if it was explicitly turned off.
Thankfully TLS for disks was only used with the vxhs protocol so hardly
anybody would ever be able to hit the problem.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJiri Denemark <jdenemar@redhat.com>

src/qemu/qemu_hotplug.c

@@ -468,7 +468,7 @@ qemuDomainAttachDiskGeneric(virQEMUDriverPtr driver,
     else if (rv > 0)
         prdStarted = true;
 
-    if (disk->src->haveTLS &&
+    if (disk->src->haveTLS == VIR_TRISTATE_BOOL_YES &&
         qemuDomainAddDiskSrcTLSObject(driver, vm, disk->src) < 0)
         goto error;