DHCP client option 61 "client_id"

the existing seeting of client_id to a VPP version number was unused and so overridden

Change-Id: If9ebea936336f1fcca8d07e67186c95f8f8f0ccd
Signed-off-by: Neale Ranns <nranns@cisco.com>
diff --git a/src/vnet/dhcp/dhcp.api b/src/vnet/dhcp/dhcp.api
index a280372..c632c08 100644
--- a/src/vnet/dhcp/dhcp.api
+++ b/src/vnet/dhcp/dhcp.api
@@ -61,6 +61,7 @@
     @param context - sender context, to match reply w/ request
     @param sw_if_index - index of the interface for DHCP client
     @param hostname - hostname
+    @param client_id - Client ID - option 61
     @param is_add - add the config if non-zero, else delete
     @param want_dhcp_event - DHCP event sent to the sender
            via dhcp_compl_event API message if non-zero
@@ -72,6 +73,7 @@
   u32 context;
   u32 sw_if_index;
   u8 hostname[64];
+  u8 client_id[64];
   u8 is_add;
   u8 want_dhcp_event;
   u32 pid;