wave5: decoder: Increase buffer offset for dmabuf import case

commit f6f812cfa29f7a8136ebf62c604b1d7fefbcee8e from
git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git



The number of free buffers allowed in downstream pool was 2,
is increased to 3 to support the lag free streaming of decoded
data to the downstream pool.

Signed-off-by: Prasanth Babu Mantena <p-mantena@ti.com>
Acked-by: Darren Etheridge <detheridge@ti.com>
Signed-off-by: Xulin Sun <xulin.sun@windriver.com>