SMP: Use correct SMP pair fail reason

The pairing failure reason sent from remote devices
is not read correctly from packet, this CL fixes it.

Bug: 320745565
Bug: 320744382

Test: m com.android.btservices | Manual Start SMP pairing to a
peer device, then reject pairing at the peer side and check the
pairing failure reason in logs.

Change-Id: Ie6829ea218bd507ff73d8803b49bb458773b5cfb