qom: Don't use 'gen': false for qom-get, qom-set, object-add

With the previous commit, the generated marshalers just work, and save
us a bit of handwritten code.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1442401589-24189-23-git-send-email-armbru@redhat.com>
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 6a21bd6..8808ae6 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -40,6 +40,7 @@
 returns_whitelist = [
     # From QMP:
     'human-monitor-command',
+    'qom-get',
     'query-migrate-cache-size',
     'query-tpm-models',
     'query-tpm-types',