zebra: multiple vlan aware bridge datastructure changes and vxlan device iftype deriv...

zebra: multiple vlan aware bridge datastructure changes and vxlan device iftype derivation from netlink

This change set introduces data structure changes required for multiple vlan aware bridge
functionality. A new structure zebra_l2_bridge_if encapsulates the vlan to access_bd
association of the bridge. A vlan_table hash_table is used to record each instance
of the vlan to access_bd of the bridge via zebra_l2_bridge_vlan structure.

vxlan iftype derivation: netlink attribute IFLA_VXLAN_COLLECT_METADATA is used
to derive the iftype of the vxlan device. If the attribute is present, then the
vxlan interface is treated as single vxlan device, otherwise it would default to
traditional vxlan device.

zebra_vxlan_check_readd_vtep, zebra_vxlan_dp_network_mac_add/del is modified to
be vni aware.

mac_fdb_read_for_bridge - is modified to be (vlan, bridge) aware

Signed-off-by: Sharath Ramamurthy <sramamurthy@nvidia.com>