asoc: set AFE_LOOPBACK_TX port id to EC ref port

- AFE_LOOPBACK_TX BE is the dummy backend created to
  establish the EC reference capture path. While
  opening COPP pass playback port id instead of
  AFE_LOOPBACK_TX to get reference stream data from
  AFE RX port.
- Add session type support in creating new COPP and
  while checking for existing COPP.

CRs-Fixed: 2080421
Change-Id: I979f3ce1009cc18ff14130bebb8bd51a78fbe5ac
Signed-off-by: Surendar Karka <skarka@codeaurora.org>