fb: via: turn gpiolib and i2c selects into dependencies

Device driver should not directly select subsystems. In this case
we get build warnings like

warning: (ARCH_REQUIRE_GPIOLIB && PINCTRL_AT91 && PINCTRL_NOMADIK && MFD_TC6393XB && FB_VIA) selects GPIOLIB which has unmet direct dependencies (ARCH_WANT_OPTIONAL_GPIOLIB || ARCH_REQUIRE_GPIOLIB)

which we can avoid using the normal 'depends on' statement.

Also, this patch makes it possible for DRM drivers to have a dependency
on GPIOLIB without getting circular Kconfig dependencies.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>