hal: update active input to always refer last started input

Active input reference is used to configure params common across
different sessions. This is reset to NULL, if any open input is closed.
Since hal can have multiple inputs, active input reference should be
set to the one still active and started most recently.

CRs-Fixed: 1074966
Change-Id: Ic4bc02f74f7921698713666c84e642ed4807aed0