hal: fix channel mask for m-ch offload playback

- Update channel mask with compress parameters for
  compress offload playback on HDMI device

Change-Id: I89263f56923588fcb906facfd4ae9ebf95203743
audio: Re-arrange member var initializations

Rearrange initializations of some stream_out member
variables to prevent possible uninitialized use.

CRs-Fixed: 587676
Change-Id: I7018f38f29a19b130185b285f4acf22219e4228c