fix mem leak in handle_cmd_ps(): free luop

Each GSUP client creates a luop, but since lu_op_tx_del_subscr_data() doesn't
free the luop, each allocated luop leaks memory.

Change-Id: If912dc992bc7f18c49d22ec0436d9679c1cd04f6
diff --git a/src/ctrl.c b/src/ctrl.c
index 8682e14..74172c4 100644
--- a/src/ctrl.c
+++ b/src/ctrl.c
@@ -54,6 +54,7 @@
 			luop = lu_op_alloc_conn(co);
 			lu_op_fill_subscr(luop, ctx->dbc, cmd->value);
 			lu_op_tx_del_subscr_data(luop);
+			lu_op_free(luop);
 		}
 	}