Bluetooth: btrtl: Add null check in setup

btrtl_dev->ic_info is only available from the controller on cold boot
(the lmp subversion matches the device model and this is used to look up
the ic_info). On warm boots (firmware already loaded),
btrtl_dev->ic_info is null.

Fixes: 05672a2c

 (Bluetooth: btrtl: Enable central-peripheral role)
Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>