media: mediatek: vcodec: Can't set dst buffer to done when lat decode error

Core thread will call v4l2_m2m_buf_done to set dst buffer done for
lat architecture. If lat call v4l2_m2m_buf_done_and_job_finish to
free dst buffer when lat decode error, core thread will access kernel
NULL pointer dereference, then crash.

Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>