Deprecate HMP `cpu-add`

Since we're deprecating the QMP `cpu-add`, let's deprecate its HMP
equivalent, too.
Suggested-by: NThomas Huth <thuth@redhat.com>
Signed-off-by: NKashyap Chamarthy <kchamart@redhat.com>
Message-Id: <20181030123526.26415-3-kchamart@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>

hmp-commands.hx

@@ -1849,14 +1849,16 @@ ETEXI
         .name       = "cpu-add",
         .args_type  = "id:i",
         .params     = "id",
-        .help       = "add cpu",
+        .help       = "add cpu (deprecated, use device_add instead)",
         .cmd        = hmp_cpu_add,
     },
 
 STEXI
 @item cpu-add @var{id}
 @findex cpu-add
-Add CPU with id @var{id}
+Add CPU with id @var{id}.  This command is deprecated, please
++use @code{device_add} instead. For details, refer to
+'docs/cpu-hotplug.rst'.
 ETEXI
 
     {

hmp.c

@@ -2372,6 +2372,8 @@ void hmp_cpu_add(Monitor *mon, const QDict *qdict)
     int cpuid;
     Error *err = NULL;
 
+    error_report("cpu_add is deprecated, please use device_add instead");
+
     cpuid = qdict_get_int(qdict, "id");
     qmp_cpu_add(cpuid, &err);
     hmp_handle_error(mon, &err);