Introduce default rx mode for device drivers

If interface is down and queues are not configured then we are not able
to change rx-mode. This change introducess default mode which is stored
per interface and applied if driver wants.

Change-Id: I70149c21c1530eafc148d5e4aa03fbee53dec62f
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/vnet/devices/devices.c b/src/vnet/devices/devices.c
index e3311c4..f64c6e0 100644
--- a/src/vnet/devices/devices.c
+++ b/src/vnet/devices/devices.c
@@ -245,6 +245,9 @@
   vnet_device_input_runtime_t *rt;
   int is_polling = 0;
 
+  if (mode == VNET_HW_INTERFACE_RX_MODE_DEFAULT)
+    mode = hw->default_rx_mode;
+
   if (hw->input_node_thread_index_by_queue == 0 || hw->rx_mode_by_queue == 0)
     return VNET_API_ERROR_INVALID_INTERFACE;