rocker: return -ENOMEM in case of some world alloc fails

Until now, 0 is returned in this error case. Fix it ro return -ENOMEM.
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>

hw/net/rocker/rocker.c

@@ -1301,6 +1301,7 @@ static int pci_rocker_init(PCIDevice *dev)
 
     for (i = 0; i < ROCKER_WORLD_TYPE_MAX; i++) {
         if (!r->worlds[i]) {
+            err = -ENOMEM;
             goto err_world_alloc;
         }
     }