hal: Fix backend for 24 bit playback on speaker

Configure backend at 48khz for 24 bit playback on speakers.
Currently, ADM can be configured only at the begining of stream
playback. During device switch, in the middle of a playback, the
backend remains at the previous configuration.
By allowing ADM and backend re-configuration during playback, 24-bit
playback is enforced on appropriate backend.

Change-Id: I6a6df5699972b0992a217fb2a4c9dc94fd2230ce