media: solo6x10: export hardware GPIO pins 8:31 to gpiolib interface

24 GPIO pins from 32 available on solo6x10 chips are exported
to gpiolib. First 8 GPIOs are reserved for internal use on capture card
boards, GPIOs in range 8:15 are configured as outputs to control relays,
remaining 16:31 are configured as inputs to read sensor states.
Now with this patch userspace DVR software can switch relays and read
sensor states when GPIO extension cards are attached to Softlogic solo6x10
based video capture cards.

Signed-off-by: Anton Sviridenko <anton@corp.bluecherry.net>
Signed-off-by: Ismael Luceno <ismael@iodev.co.uk>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>