The backlight changes that went in had a bug where they could cause the
kernel to access an unitialized pointer when blanking if there is no
backlight control on a machine.
The bug affects atyfb, aty128fb, nvidiafb and rivafb. radeonfb seems to
be ok. This fixes it.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>