Bluetooth: Ignore isochronous endpoints for Intel USB bootloader

The isochronous endpoints are not valid when the Intel Bluetooth
controller boots up in bootloader mode. So just mark these endpoints
as broken and then they will not be configured.

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