lib: lacplib: support OpenFlow1.2/1.3

Signed-off-by: itoyuichi <ito.yuichi0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
lib: lacplib: add underscore to a protected member

Signed-off-by: itoyuichi <ito.yuichi0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
lib: lacplib: correct comments

Signed-off-by: itoyuichi <ito.yuichi0@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>