Fix compile without Bluetooth LE stack included

Commit 29f2e9c... ("Bluetooth: Implementation of LPP and extended LE
scan") breaks the compile on devices which don't include Bluetooth LE
support.  Fix the breakage by guarding new code which depends on the BLE
stack with #ifdefs.

Change-Id: I823673ffe64f08b060ec0db59f40c724b61ff345