ASoC: msm: add platform routing for voice call via MI2S use case

There can be board design which MI2S block is connected to external
CODEC. External CODEC can be used for voice call purpose.
Enable routing so voice call downlink, uplink, echo
cancellation can be transferred to off-chip modem.

Change-Id: Id240eb5ba4fcea52c5e261e2c09610fcbb718d65
Signed-off-by: Patrick Lai <plai@codeaurora.org>