Use larger capture pipe since we support resampling by 6:1

This avoids overruns on the client AudioRecord side,
without requiring client to use a large buffer.
It should not increase input latency, since a newly started AudioRecord
always joins the stream starting at the latest data.

Change-Id: Ib2b8de75cc40a6a3d493a1f8b46b41220f69264f