Bluetooth: btbcm: Bail sooner from btbcm_initialize() when not loading fw

If we have already loaded the firmware/patchram and btbcm_initialize()
is called to re-init the HCI after this then there is no need to get
the USB device-ids and build a firmware-filename out of these.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>