V4L/DVB (13366): em28xx: fix Reddo DVB-C USB TV Box GPIO

Set device GPIOs only once. There is no need for .dvb_gpio to select
between analog and digital because device is digital only.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>