Commit d6c34c4644 changed the behavior
slightly but didn't update the documentation. The callback will now be
reset to NULL once the key is generated. Calling bt_pub_key_gen()
multiple times before the key is finished would result in creation of an
infinite loop. This could happen when an application calls mesh_init()
and mesh_reset() in quick succession. Clarify the behavior of the API in
the documentation.
Also passing a NULL argument would result in an undefined behavior, so
add a check to match the behavior described in documentation.
Signed-off-by: Michał Narajowski <michal.narajowski@codecoup.pl>
f62a40beb6