qmp: hide "hotplugged" device property from device-list-properties

The "hotplugged" device property was not reported before commit
f4eb32b590bf58c1c67570775eb78beb09964fad ("qmp: show QOM properties in
device-list-properties").  Fix this difference.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/qmp.c b/qmp.c
index 0d2553a..c6767c4 100644
--- a/qmp.c
+++ b/qmp.c
@@ -509,6 +509,7 @@
         if (strcmp(prop->name, "type") == 0 ||
             strcmp(prop->name, "realized") == 0 ||
             strcmp(prop->name, "hotpluggable") == 0 ||
+            strcmp(prop->name, "hotplugged") == 0 ||
             strcmp(prop->name, "parent_bus") == 0) {
             continue;
         }