Bluetooth: L2CAP: Fix L2CAP_CR_SCID_IN_USE value

Fix issue found during L2CAP qualification test TP/LE/CFC/BV-20-C.

Signed-off-by: Marcin Kraglak <marcin.kraglak@tieto.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>