Warnings from include/linux/gpio/consumer.h with CONFIG_GPIOLIB=n

[Florian Fainelli]

Hi Linus,

I think Sergei or someone else was mentioning that before a while ago,
but when CONFIG_GPIOLIB=n most gpiod_* inline stubs have WARN_ON() that
will scare people.

What do you recommend doing for code that might be built with or without
CONFIG_GPIOLIB, should we just encapsulate the part that deals with
GPIOs under an #if IS_ENABLED(CONFIG_GPIOLIB) or something? The
particular piece of code that I just saw this with is
drivers/net/phy/mdio_bus.c.

Thanks!
-- 
Florian