bgpd: Enable support for BGP IPV6 multipath.

This commit adds these two commands:
maximum-paths <1-MULTIPATH_NUM>
maximum-paths ibgp <1-MULTIPATH_NUM>

under address-family ipv6 mode.  In addition adding the ability
to pass multiple paths down into zebra from bgp.

Signed-off-by: Ayan Banerjee <ayan@cumulusnetworks.com>
Signed-off-by: Dinesh G Dutt <ddutt@cumulusnetworks.com>
Reviewed-by: Scott Feldman <sfeldma@cumulusnetworks.com>
diff --git a/bgpd/bgp_vty.c b/bgpd/bgp_vty.c
index 925e267..0b32625 100644
--- a/bgpd/bgp_vty.c
+++ b/bgpd/bgp_vty.c
@@ -9915,12 +9915,18 @@
   install_element (BGP_IPV4_NODE, &bgp_maxpaths_cmd);
   install_element (BGP_IPV4_NODE, &no_bgp_maxpaths_cmd);
   install_element (BGP_IPV4_NODE, &no_bgp_maxpaths_arg_cmd);
+  install_element (BGP_IPV6_NODE, &bgp_maxpaths_cmd);
+  install_element (BGP_IPV6_NODE, &no_bgp_maxpaths_cmd);
+  install_element (BGP_IPV6_NODE, &no_bgp_maxpaths_arg_cmd);
   install_element (BGP_NODE, &bgp_maxpaths_ibgp_cmd);
   install_element (BGP_NODE, &no_bgp_maxpaths_ibgp_cmd);
   install_element (BGP_NODE, &no_bgp_maxpaths_ibgp_arg_cmd);
   install_element (BGP_IPV4_NODE, &bgp_maxpaths_ibgp_cmd);
   install_element (BGP_IPV4_NODE, &no_bgp_maxpaths_ibgp_cmd);
   install_element (BGP_IPV4_NODE, &no_bgp_maxpaths_ibgp_arg_cmd);
+  install_element (BGP_IPV6_NODE, &bgp_maxpaths_ibgp_cmd);
+  install_element (BGP_IPV6_NODE, &no_bgp_maxpaths_ibgp_cmd);
+  install_element (BGP_IPV6_NODE, &no_bgp_maxpaths_ibgp_arg_cmd);
 
   /* "timers bgp" commands. */
   install_element (BGP_NODE, &bgp_timers_cmd);