Dynamic policies: support for device selection

Dynamic policy mix: rename "registration" field to device address
  as this reflects the true use of the field.
AudioPolicyManager: dynamic policy registration differs depending
  on policy routing flags.
When register a mix with the RENDER flag, iterate over all outputs'
  patches to find a matching device and address.

Bug 25448664

Change-Id: I71584081e7f1b2b5252fb6c4659fdeb464f7d282