net: ipv6: For kerneldoc warnings with W=1

net: ipv6: For kerneldoc warnings with W=1

net/ipv6/addrconf.c:2005: warning: Function parameter or member 'dev' not described in 'ipv6_dev_find'
net/ipv6/ip6_vti.c:138: warning: Function parameter or member 'ip6n' not described in 'vti6_tnl_bucket'
net/ipv6/ip6_tunnel.c:218: warning: Function parameter or member 'ip6n' not described in 'ip6_tnl_bucket'
net/ipv6/ip6_tunnel.c:238: warning: Function parameter or member 'ip6n' not described in 'ip6_tnl_link'
net/ipv6/ip6_tunnel.c:254: warning: Function parameter or member 'ip6n' not described in 'ip6_tnl_unlink'
net/ipv6/ip6_tunnel.c:427: warning: Function parameter or member 'raw' not described in 'ip6_tnl_parse_tlv_enc_lim'
net/ipv6/ip6_tunnel.c:499: warning: Function parameter or member 'skb' not described in 'ip6_tnl_err'
net/ipv6/ip6_tunnel.c:499: warning: Function parameter or member 'ipproto' not described in 'ip6_tnl_err'
net/ipv6/ip6_tunnel.c:499: warning: Function parameter or member 'opt' not described in 'ip6_tnl_err'
net/ipv6/ip6_tunnel.c:499: warning: Function parameter or member 'type' not described in 'ip6_tnl_err'
net/ipv6/ip6_tunnel.c:499: warning: Function parameter or member 'code' not described in 'ip6_tnl_err'
net/ipv6/ip6_tunnel.c:499: warning: Function parameter or member 'msg' not described in 'ip6_tnl_err'
net/ipv6/ip6_tunnel.c:499: warning: Function parameter or member 'info' not described in 'ip6_tnl_err'
net/ipv6/ip6_tunnel.c:499: warning: Function parameter or member 'offset' not described in 'ip6_tnl_err'

ip6_tnl_err() is an internal function, so remove the kerneldoc. For
the others, add the missing parameters.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20201031183044.1082193-1-andrew@lunn.ch
Signed-off-by: Jakub Kicinski <kuba@kernel.org>