ila: ipv6/ila: fix nlsize calculation for lwtunnel

The handler 'ila_fill_encap_info' adds two attributes: ILA_ATTR_LOCATOR
and ILA_ATTR_CSUM_MODE.

nla_total_size_64bit() must be use for ILA_ATTR_LOCATOR.

Also, do nla_put_u8 instead of nla_put_u64 for ILA_ATTR_CSUM_MODE.

Fixes: f13a82d8 ("ipv6: use nla_put_u64_64bit()")
Fixes: 90bfe662

 ("ila: add checksum neutral ILA translations")
Reported-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>