net: bridge: Describe @tunnel_hash member in net_bridge_vlan_group struct

Sphinx reports kernel-doc warning:

WARNING: ./net/bridge/br_private.h:267 struct member 'tunnel_hash' not described in 'net_bridge_vlan_group'

Fix it by describing @tunnel_hash member.

Fixes: efa5356b0d9753 ("bridge: per vlan dst_metadata netlink support")
Signed-off-by: Bagas Sanjaya <[e-mail]>
Acked-by: Nikolay Aleksandrov <[e-mail]>
Reviewed-by: Ido Schimmel <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

net/bridge/br_private.h

···
  * struct net_bridge_vlan_group
  *
  * @vlan_hash: VLAN entry rhashtable
+ * @tunnel_hash: Hash table to map from tunnel key ID (e.g. VXLAN VNI) to VLAN
  * @vlan_list: sorted VLAN entry list
  * @num_vlans: number of total VLAN entries
  * @pvid: PVID VLAN id