Bluetooth: Making Intent for pairing in foreground.

During BT ON when headset is previously connected and second
device is trying to pair, Intent ACTION_PAIRING_REQUEST is
not received by application in time.
Changes made to make ACTION_PAIRING_REQUEST in foreground.

CRs-Fixed: 612574

Change-Id: I6b98fbb73a1b1f2d1794f02713578d24988e456f