V4L/DVB (3291): Fix signed/unsigned bug in hue handling

- Fix signed/unsigned bug in hue handling (set to -127 and 129 was returned).

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@brturbo.com.br>