Bluetooth: Remove unnecessary deferred work for SMP key distribution

Now that the identity address update happens through its own deferred
work there's no need to have smp_distribute_keys anymore behind a second
deferred work. This patch removes this extra construction and makes the
code do direct calls to smp_distribute_keys() again.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>