ASoC: qdsp6v2: Avoid closing AFE port when it is in use

AUXPCM AFE ports share the same clock for Tx and Rx operations.
Add logic to avoid shutting down clock and PCM AFE ports for
one type of operation (Tx/Rx) when the other operation is still
ON.

Change-Id: I2029c699dfdca796548bbd85167bdbd3328d4ca6
CRs-fixed: 489142, 498589
Signed-off-by: Banajit Goswami <bgoswa@codeaurora.org>