Bluetooth: btintel: fix warning

Fix compilation the following compilation warning, which happens when
CONFIG_BT_INTEL is not set:

  drivers/bluetooth/btintel.h:98:13: warning: ‘btintel_version_info’
  defined but not used [-Wunused-function]
   static void btintel_version_info(struct hci_dev *hdev,
                                    struct intel_version *ver)
               ^

Signed-off-by: Vincent Stehlé <vincent.stehle@laposte.net>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>