Bluetooth: Refactor deferred setup test in rfcomm_dlc_close()

Prepare for directly closing dlc if the RFCOMM session has not
yet been started; refactor the deferred setup test for only those
dlc states to which the test applies. Retains functional
equivalence.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Tested-By: Alexander Holler <holler@ahsoftware.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>