V4L/DVB: gspca- ov534: Remove ambiguous controls

Remove Blue/Red Channel Target Value, they are meant for Black Level
Calibration but it is not completely clear how to use them.

Signed-off-by: Max Thrun <bear24rw@gmail.com>
Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>