[media] gspca_stv06xx: Convert to the control framework

HdG:
1) Let the gspca-core cleanup the controls on control-init error, like
with the other converted sub drivers
2) Note this also fixes a bug in the hdcs1020 support which was wrongly
reporting an exposure range of 0-65535, even though the effective range was
only 0-255

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>