media: coda: Remove unbalanced and unneeded mutex unlock

commit 766b9b16 upstream.

The mutex unlock in the threaded interrupt handler is not paired
with any mutex lock. Remove it.

This bug has been here for a really long time, so it applies
to any stable repo.

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>