qdsp6v2: Fix issue with DAP effects not getting applied on WFD

DAP effects does not get applied on WFD. This is because device
mapping array uses the ds2 devices count instead of iterating
through all the devices. The index for proxy device is less than
the count for ds2 devices. This results in proxy device not
activated for DAP.

CRs-Fixed: 702798
Change-Id: If785683d1c6cfcc6257337cc731692c678c1f586
Signed-off-by: Krishnankutty Kolathappilly <kkolat@codeaurora.org>