[media] adv7604/cobalt: Allow compile test if !GPIOLIB

The GPIO subsystem provides dummy GPIO consumer functions if GPIOLIB is
not enabled. Hence drivers that depend on GPIOLIB, but use GPIO consumer
functionality only, can still be compiled if GPIOLIB is not enabled.

Relax the dependency of VIDEO_ADV7604 and VIDEO_COBALT (the latter
selects the former) on GPIOLIB if COMPILE_TEST is enabled.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>