Security: Fix flow for ClassicPairingHandler

It seems that on the controller after we give the
link key request reply with the correct link key
the controller is happy.

Bug: 162455705
Test: atest --host bluetooth_test_gd
Test: cert/run --host SecurityTest
Test: cert/run --host LeSecurityTest
Tag: #gd-refactor
Change-Id: I1a6382367cac095171aa859605b77dcc5b62b6f9