ASoC: msm: qdsp6v2: Update the routing for aux pcm usecase

Audio can be looped back between primary and secondary aux pcm
for some of the usecases.
Change adds routing table entry and support for allowing loopback.

Change-Id: I4166f601edae4cf89423e35345b0c1b8ddfbb000
CRs-fixed: 508098
Signed-off-by: Gopikrishnaiah Anandan <agopik@codeaurora.org>