Full volume on remote submix for apps that need it

If an AudioRecord is created with the "fixedVolume" tag
  when recording from REMOTE_SUBMIX, treat the
  device DEVICE_OUT_REMOTE_SUBMIX as a fixed full volume
  device during the recording. Also register a death
  handler during the recording.
  Otherwise this is a no-op.

Bug 17635294

Change-Id: I8d26fe777047126f34308e1e1b7ac28ba269ad89