V4L/DVB (12347): cx25840: Bugfix for no DVB-T on the Hauppauge HVR-1700

After the i2c subdev changes the ordering of initialization changed,
causing a total loss of previous GPIO settings and a loss of DTV.
The generic firmware loading routine has now changed to preserve
GPIO values if the device is cx23885 based (safety) and I've
moved the GPIO configuration from probe() into the cx23885 init
func which is a little clearer and fixes the bug.

Tested-by: Sohail Syyed <linuxtv@hubstar.net>
Reviewed-by: Michael Krufky <mkrufky@kernellabs.com>
Signed-off-by: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>