Bluetooth: GAP: Disconnect ACL immediately after Auth failure.

The patch fixes issue of ACL lingering for 2 seconds after
Authentication failure. Another Auth request during this
time results in improper connection reference and hence
resulting in ACL to persist forever if remote doesn't
disconnect.

Change-Id: Ief920af97d8f27e93460130dc86113b40dc5f6a5
Signed-off-by: Mallikarjuna GB <gbmalli@codeaurora.org>