Bluetooth: Add SMP confirmation structs

This patch adds initial support for verifying the confirmation value
that the remote side has sent.

Signed-off-by: Anderson Briglia <anderson.briglia@openbossa.org>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@openbossa.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>