parallels: Fix false error messages in libvirt log

There was many errors in libvirt.log caused by prlsdkDelNet function because
job variable was always initialized as PRL_INVALID_HANDLE
In this patch job variable gets return value of PrlSrv_DeleteVirtualNetwork function()

src/vz/vz_sdk.c

@@ -2900,7 +2900,7 @@ static void prlsdkDelNet(vzConnPtr privconn, virDomainNetDefPtr net)
     pret = PrlVirtNet_SetNetworkId(vnet, net->data.network.name);
     prlsdkCheckRetGoto(pret, cleanup);
 
-    PrlSrv_DeleteVirtualNetwork(privconn->server, vnet, 0);
+    job = PrlSrv_DeleteVirtualNetwork(privconn->server, vnet, 0);
     if (PRL_FAILED(pret = waitJob(job)))
         goto cleanup;