policy-hal: fix glitch in playback while applying setForceUse

- Headset and Speaker shares same backend on our platform,
  because of which routing of a stream from one device to another
  affects other streams on these devices as well
- Reduce the impact of resultant glitch by processing routing request
  on LL output at the end, since LL output is used mostly for
  non-music playback and is less sensitive to the impact of routing
  from any other output's context.

Change-Id: I9fa3a7b49529ace5c28e82b788ffbfd612d59791