ASoC: msm: qdsp6v2: add path to support external EC reference

Addition of a routing path to connect VoLTE and VoIP
uplink with MI2S Tx port. This change is required if
external EC is to be used with external speaker.

CRs-Fixed: 622500
Signed-off-by: Avinash Vaish <avaish@codeaurora.org>
Change-Id: Ic3f7b7b43235623696fd610bc0b459633f0cd7c2