Set LE link as authenticated if encrypted with authenticated LTK

On encryption after reconnection, the link was not designated as authenticated even if the LTK was authenticated. In such case, SMP security request from the remote deivce with MTIM protection requirement triggers the re-pairing attempt from the stack.

Change-Id: Idf65f9d18302fa15235d83c93d4d345a11f90293
Test: Reconnect with LE devices
Test: m
Bug: 290799434