Don't process pair request when controller is not ready

Use case: when one application is trying to pair and
other application is turning off Bluetooth.

Steps: when one application is trying to pair and
other application is turning off Bluetooth.

Failure: Bluetooth process crashed.

Root Cause: Bluetooth process crashed due to assertion,
as controller module is not ready.

Fix: Made a checks for controller module is ready or not, If
it is ready then only go for pairing.

Change-Id: I72c72f6b5545c845e79874212359854023ffad98