rpc: don't unref service ref on socket behalf twice

Second unref was added in [1]. We don't need it actually as
we pass free callback to virNetSocketAddIOCallback thus
when we call virNetSocketRemoveIOCallback the extra ref for
callback will be dropped without extra efforts.

[1] 355d8f470f: virNetServerServiceClose: Don't leak sockets

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>

src/rpc/virnetserverservice.c

@@ -449,6 +449,5 @@ void virNetServerServiceClose(virNetServerServicePtr svc)
     for (i = 0; i < svc->nsocks; i++) {
         virNetSocketRemoveIOCallback(svc->socks[i]);
         virNetSocketClose(svc->socks[i]);
-        virObjectUnref(svc);
     }
 }