media: iris: Add codec specific check for VP9 decoder drain handling

Add a codec specific for the VP9 decoder to ensure that a non-null
buffer is sent to the firmware during drain. The firmware enforces a
check for VP9 decoder that the number of buffers queued and dequeued on
the output plane should match. When a null buffer is sent, the firmware
does not return a response for it, leading to a count mismatch and an
assertion failure from the firmware.

Acked-by: Vikash Garodia <quic_vgarodia@quicinc.com>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-QRD
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-HDK
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-HDK
Signed-off-by: Dikshita Agarwal <quic_dikshita@quicinc.com>
Tested-by: Vikash Garodia <quic_vgarodia@quicinc.com> # on sa8775p-ride
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>