media: si470x-i2c: Use managed resource helpers

Simplify cleanup of failures by using managed resource helpers

Signed-off-by: Pawe? Chmiel <pawel.mikolaj.chmiel@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>