media: mtk-jpeg: cancel workqueue on release for supported platforms only

media: mtk-jpeg: cancel workqueue on release for supported platforms only

Since a recent fix the mtk_jpeg_release function cancels any pending
or running work present in the driver workqueue using
cancel_work_sync function.
Currently, only the multicore based variants use this workqueue and they
have the jpeg_worker platform data field initialized with a workqueue
callback function. For the others, this field value remain NULL by
default.
The cancel_work_sync function is unconditionally called in
mtk_jpeg_release function, even for the variants that do not use the
workqueue. This call generates a WARN_ON print in __flush_work because
the workqueue callback function presence check fails in __flush_work
function (used by cancel_work_sync).

So, to avoid these warnings, call cancel_work_sync only if a workqueue
callback is defined in platform data.

Fixes: 34c519feef3e ("media: mtk-jpeg: fix use-after-free in release path due to uncancelled work")
Cc: stable@vger.kernel.org
Signed-off-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>