target-openrisc: Catch attempt to instantiate abstract type in cpu_init()

There is no abstract OpenRISCCPU yet, but that seems a bug of its own.

Cc: qemu-stable@nongnu.org
Signed-off-by: NAndreas Färber <afaerber@suse.de>

target-openrisc/cpu.c

@@ -98,7 +98,8 @@ static ObjectClass *openrisc_cpu_class_by_name(const char *cpu_model)
     }
 
     oc = object_class_by_name(cpu_model);
-    if (oc != NULL && !object_class_dynamic_cast(oc, TYPE_OPENRISC_CPU)) {
+    if (oc != NULL && (!object_class_dynamic_cast(oc, TYPE_OPENRISC_CPU) ||
+                       object_class_is_abstract(oc))) {
         return NULL;
     }
     return oc;