Now interface is supposing that you setting protinfo attrs for link one
by one. But you can get all protinfo attrs with one call.
Signed-off-by: Alexander Morozov <lk4d4@docker.com>
Added new `Protinfo` datastructure, which contains fields from
`IFLA_PROTINFO | NLA_F_NESTED`. It is not embedded to `LinkAttrs`
because we need to use `NLM_F_DUMP` requests to get that info.
Signed-off-by: Alexander Morozov <lk4d4@docker.com>