asoc: update passthrough mode in transcode loopback driver

Update passthrough mode to pick proper path type for
compressed input data port in transcode loopback driver
to support compressed input in DSP loopback.

Change-Id: Ib2f66b467456787e08265a0da2bd85bb881a5d61
Signed-off-by: Siddartha Shaik <sshaik@codeaurora.org>
Signed-off-by: Surendar Karka <skarka@codeaurora.org>