Bluetooth: Security: Add Null check during pairing cancel intent.

Added null check, so before posing event we can restrict events,
if cached device list is empty

Change-Id: I458d181abe5eec2497b80b1713ddbc3502b79786
CRs-Fixed: 546364
(cherry picked from commit 7d7222c3e5c1054b4e2f3e59cc40cb182a72b040)
(cherry picked from commit 8ce523155dd030d82c32cf502d317023b017645b)
(cherry picked from commit 938686e749bca911e5f63150223116d1c381da8e)
Bluetooth: Remove out of range devices after ScanComplete

Change to remove device from UI when Bluetooth of remote
device is off or not discoverable anymore. Without this
change a device that discovered previously is available
in available devices list always, though the remote device
is not discoverable anymore. The current change updates
available devices list on scan complete removing the
devices that are available in cached devices and are not
discoverable anymore.

CRs-Fixed: 523374
Change-Id: Ia250d52e6fb7a69af242c961d33027f1e724ab25
(cherry picked from commit fee7b100ff7ac4eb7117ec1bc5c592d0c7adbbf8)
(cherry picked from commit 38d07978c7fb4f40af96b9fb96af09a64ce5bfff)
(cherry picked from commit 28a27af31eac45f4b3fe5932240dc437a37dda5c)