dhcp: fix unicast pkts, clean up state machine

Send dhcp unicast packets to ip4-lookup. Otherwise, these packets
won't reach a dhcp server on a different subnet.

Do an immediate client scan after processing wakeup events.

Calculate the next process wakeup time by scanning all
clients.

Increase maximum (idle, no-clients-configured) timeout to 1000
seconds.

Reduce log spew.

Type: fix
Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I3d10cd4c353298ed0b19e7e30887dc1d8d07b19e

src/plugins/dhcp/client.h

@@ -108,8 +108,6 @@ typedef struct dhcp_client_t_
   u8 client_hardware_address[6];
   u8 client_detect_feature_enabled;
 
-  /* the unicast adjacency for the DHCP server */
-  adj_index_t ai_ucast;
   /* the broadcast adjacency on the link */
   adj_index_t ai_bcast;
   /* IP DSCP to set in sent packets */
@@ -125,6 +123,9 @@ typedef struct
   uword *client_by_sw_if_index;
   u32 seed;
 
+  /* ip4-lookup node index */
+  u32 ip4_lookup_node_index;
+
   /* convenience */
   vlib_main_t *vlib_main;
   vnet_main_t *vnet_main;