qdsp6v2: Add support for suspend command for WMA decoder

WMA DSP decoder consumes more power in pause state. This is because
WMA decoder expects suspend command after it is paused. Add support
for suspend command.

Change-Id: Ifdfccb6cf6270db5b131a65f17edac40ef1a85db
CRs-Fixed: 553828
Signed-off-by: Alexy Joseph <alexyj@codeaurora.org>