Bluetooth: Fix removing of RFCOMM DLC timer with DEFER_SETUP

There is a missing call to rfcomm_dlc_clear_timer in the case that
DEFER_SETUP is used and so the connection gets disconnected after the
timeout even if it was successfully accepted previously.

This patch adds a call to rfcomm_dlc_clear_timer to rfcomm_dlc_accept
which will get called when the user accepts the connection by calling
read() on the socket.

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