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

Pseudo 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
port.

Change-Id: I00384de1104399853743e709f53f969842ef69a1
Signed-off-by: Sujin Panicker <spanic@codeaurora.org>