fbdev: rework backlight dependencies

Rather than having CONFIG_FB_BACKLIGHT select CONFIG_BACKLIGHT_CLASS_DEVICE,
make any driver that needs it have a dependency on the class device
being available, to prevent circular dependencies.

This is the same way that the backlight is already treated for the DRM
subsystem.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
5 files changed