cpu: Never skip CPU model name check in ppc64 driver

ppc64Compute(), called by cpuNodeData(), is used not only to retrieve
the driver-specific data associated to a guest CPU definition, but
also to check whether said guest CPU is compatible with the host CPU.

If the user is not interested in the CPU data, it's perfectly fine
to pass a NULL pointer instead of a return location, and the
compatibility data returned should not be affected by this. One of
the checks, specifically the one on CPU model name, was however
only performed if the return location was non-NULL.

src/cpu/cpu_ppc64.c

@@ -407,26 +407,25 @@ ppc64Compute(virCPUDefPtr host,
         !(guest_model = ppc64ModelFromCPU(cpu, map)))
         goto cleanup;
 
-    if (guestData) {
-        if (cpu->type == VIR_CPU_TYPE_GUEST &&
-            cpu->match == VIR_CPU_MATCH_STRICT &&
-            STRNEQ(guest_model->name, host_model->name)) {
-            VIR_DEBUG("host CPU model does not match required CPU model %s",
-                      guest_model->name);
-            if (message &&
-                virAsprintf(message,
-                            _("host CPU model does not match required "
-                            "CPU model %s"),
-                            guest_model->name) < 0)
-                goto cleanup;
-
-            ret = VIR_CPU_COMPARE_INCOMPATIBLE;
+    if (cpu->type == VIR_CPU_TYPE_GUEST &&
+        cpu->match == VIR_CPU_MATCH_STRICT &&
+        STRNEQ(guest_model->name, host_model->name)) {
+        VIR_DEBUG("host CPU model does not match required CPU model %s",
+                  guest_model->name);
+        if (message &&
+            virAsprintf(message,
+                        _("host CPU model does not match required "
+                        "CPU model %s"),
+                        guest_model->name) < 0)
             goto cleanup;
-        }
 
+        ret = VIR_CPU_COMPARE_INCOMPATIBLE;
+        goto cleanup;
+    }
+
+    if (guestData)
         if (!(*guestData = ppc64MakeCPUData(arch, &guest_model->data)))
             goto cleanup;
-    }
 
     ret = VIR_CPU_COMPARE_IDENTICAL;