media: mediatek: vcodec: change lat thread decode error condition

[ Upstream commit 960badda ]

If lat thread can't get lat buffer, it should be that current instance
don't be schedulded, the driver can't free the src buffer directly.

Fixes: 7b182b8d ("media: mediatek: vcodec: Refactor get and put capture buffer flow")
Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>