SPAN: Add 'is_l2" flag to DETAILS response messages.

Change-Id: I375bb0e663bc082d98a29fb101c653557ddc8f55
Signed-off-by: Jon Loeliger <jdl@netgate.com>
diff --git a/src/vnet/span/span.api b/src/vnet/span/span.api
index 8cbac7b..7b2e47c 100644
--- a/src/vnet/span/span.api
+++ b/src/vnet/span/span.api
@@ -49,10 +49,12 @@
     @param sw_if_index_from - mirorred interface
     @param sw_if_index_to - interface where the traffic is mirrored
     @param state - 0 = disabled, 1 = rx enabled, 2 = tx enabled, 3 tx & rx enabled
+    @param is_l2 - 0 = mirrored at hw device level, 1 = mirrored at l2
 */
 define sw_interface_span_details {
     u32 context;
     u32 sw_if_index_from;
     u32 sw_if_index_to;
     u8 state;
+    u8 is_l2;
 };