media: tw686x: Fix an error handling path in tw686x_probe()

The commit in Fixes: is incomplete. It has moved some code in the probe but
not all error handling paths have been updated.

Now, if request_irq() fails, we must release some resources.

Fixes: c8946454ed96 ("media: tw686x: Register the irq at the end of probe")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>