Augment Vxlan to support NSH-Proxy

PatchSet 9: add range check for decap_next_index
PatchSet 6: delete runtime range check

Change-Id: I415e156d05d09d2ff34f6578924f0b243058f464
Signed-off-by: Hongjun Ni <hongjun.ni@intel.com>
diff --git a/vpp-api-test/vat/api_format.c b/vpp-api-test/vat/api_format.c
index 9d80c42..2925c9b 100644
--- a/vpp-api-test/vat/api_format.c
+++ b/vpp-api-test/vat/api_format.c
@@ -16808,7 +16808,7 @@
 _(vxlan_add_del_tunnel,                                                 \
   "src <ip-addr> { dst <ip-addr> | group <mcast-ip-addr>\n"             \
   "{ <intfc> | mcast_sw_if_index <nn> } }\n"                            \
-  "vni <vni> [encap-vrf-id <nn>] [decap-next l2|ip4|ip6] [del]")        \
+  "vni <vni> [encap-vrf-id <nn>] [decap-next <l2|nn>] [del]")           \
 _(vxlan_tunnel_dump, "[<intfc> | sw_if_index <nn>]")                    \
 _(gre_add_del_tunnel,                                                   \
   "src <ip4-addr> dst <ip4-addr> [outer-fib-id <nn>] [teb] [del]\n")    \