btm_sec_disconnected Check if p_dev_rec is still in scope

|btm_sec_disconnected| may call the callback
|btm_cb.api.p_auth_complete_callback| which can delete |p_dev_rec|.
After deletion, |btm_sec_disconnected| still atempts to use |p_dev_rec|.

Bug: 71913396
Test: Does not crash with a quickly terminated connection.
Change-Id: Ic28beb2888a51090283be04121d785495cf25a84