Bluetooth: Handle HCI raw socket transition from unbound to bound

In case an unbound HCI raw socket is later on bound, ensure that the
monitor notification messages indicate a close and re-open. None of
the userspace tools use the socket this, but it is actually possible
to use an ioctl on an unbound socket and then later bind it.

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