[PATCH] atyfb: Fix blanking level transitions

Fix a minor problem in blanking level transitions.  Reducing the blanking
level gradually was impossible.

Signed-off-by: Ville Syrjala <syrjala@sci.fi>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>