[PATCH] lxfb: Fix console blanking

The attached patch fixes console blanking in the Geode LX framebuffer.
The current code blanks the DACs, but that does not appear to be enough
to actually blank the screen (some characters remain visible).

The new code turns off the CRT enable bit for all modes, which forces
blanking.  Also, to save power the DAC is powered down in the more 
aggressive blanking modes.  

-- 
Jordan Crouse
Systems Software Development Engineer 
Advanced Micro Devices, Inc.