L2 BD API to flush all IP-MAC entries in the specified BD

Implement API/CLI to clear IP-MAC tables used for ARP-termination
in the specified bridge domain.
The CLI to flush MAC IP tables for a BD is:
 set bridge-domain arp entry <bd-id> del-all
The API added is bd_ip_mac_flush.

Change-Id: I34ceb87c0f480c7102f6559312c24081ed485af8
Signed-off-by: John Lo <loj@cisco.com>
diff --git a/src/vnet/l2/l2_bd.h b/src/vnet/l2/l2_bd.h
index 987569a..65d3dad 100644
--- a/src/vnet/l2/l2_bd.h
+++ b/src/vnet/l2/l2_bd.h
@@ -204,6 +204,8 @@
 		       const ip46_address_t * ip_addr,
 		       const mac_address_t * mac, u8 is_add);
 
+void bd_flush_ip_mac (u32 bd_index);
+
 #endif
 
 /*