Fixed SMP pairing failure due to race condition

SMP pairing failure if remote send security request before master
side receive LE link connection callback. The racing condition will
cause master side bonding failure upon ignoring remote security request
and flush out all SMP information. Retain SMP information when a
locally initiated pairing is in process solves the problem.

Bug: 17412687
Change-Id: Ia2256160c866413f93c6f49e5db82b4c6489d9d2