Don't set CT2 bit when talking to pre-5.0 devices

Prior to 5.0 spec, CT2 bit in AuthReq was reserved. Setting it cause
bonding failure with devices that handle it incorrectly.

Bug: 66179701
Bug: 66931978
Test: Bond with device that have 4.2 chip
Change-Id: Idbbf2c39c499698844218059a35cb686996c136a