asoc: add code change for proxy playback and capture BE DAIs.

proxy AFE port based BE DAIs can be used for various use cases, including
but not limited to voice call. Add support for BE DAI link based on pseudo
ports.

Change-Id: I00384de1104399853743e709f53f969842ef69a1
Signed-off-by: Jaideep Sharma <jaidshar@codeaurora.org>