media: coda: Remove unbalanced and unneeded mutex unlock

commit 766b9b168f6c75c350dd87c3e0bc6a9b322f0013 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>