Bluetooth: btusb: BTUSB_WAKEUP_DISABLE prevents wake

When the BTUSB_WAKEUP_DISABLE flag is set, always return true for
prevent wake. This tells the suspend notifier not to prepare the
controller for reconnections during suspend.

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>