fbdev: bfin-t350mcqb-fb: avoid unused warnings in backlight code

The current backlight code is stubbed out, so the new props changes added
some warnings about unused label/prop.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>