media: mtk-jpeg: Fix timeout schedule error in mtk_jpegdec_worker.

In mtk_jpegdec_worker, if error occurs in mtk_jpeg_set_dec_dst, it
will start the timeout worker and invoke v4l2_m2m_job_finish at
the same time. This will break the logic of design for there should
be only one function to call v4l2_m2m_job_finish. But now the timeout
handler and mtk_jpegdec_worker will both invoke it.

Fix it by start the worker only if mtk_jpeg_set_dec_dst successfully
finished.

Fixes: da4ede4b ("media: mtk-jpeg: move data/code inside CONFIG_OF blocks")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Cc: stable@vger.kernel.org
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>