Bluetooth: Add new structures for supporting SM key distribution

We need these changes because SMP keys may have more information
associated with them, for example, in the LTK case, it has an
encrypted diversifier (ediv) and a random number (rand).

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