Bluetooth: Initiate dedicated bonding if pin/key missing on remote device

In case of 2.1 capable devices, when remote device had unpaired,
successive connect from the DUT was resulting in general bonding with
automatic accept allowed for numeric comparison
(i.e. authentication_requirements = 0x04). This lead to bad user
experience as user confirmation pop up wasn't notified on the DUT. Now
its ensured that if remote device has unpaired then DUT would trigger
dedicated bonding as part of the DUT intiated connect.

CRs-fixed: 362572
Change-Id: Id55f6cf3cc70621c29f583aa913fc08180e2d8f0
Signed-off-by: Royston Rodrigues <roystonr@codeaurora.org>