audio: correct routing order for voip output

Routing primary output before voip_rx output will cause unexpected
RX/TX path suddenly and unmuted voice stream during when system
plays touch sound and switches path between handset and handsfree.

Bug: 154290829
Test: manual test in VoIP

Signed-off-by: Jasmine Cha <chajasmine@google.com>
Change-Id: Ia60802ec887f0dfeaa0f93d151ba2f2c50e0d41d