From: Benjamin Herrenschmidt <benh@kernel.crashing.org>

This patch implements what we discussed earlier to fix the switch bewteen
KD_GRAPHICS and KD_TEXT.

It has been tested for a few days now and appear to resolve the problem for
affected users.

James: I know you have some objections, I don't fully agree with them, and
I want that in asap now, that bug has been plaguing fbdev since the very
beginning and it's time to get rid of that and my corresponding todolist
entry.  You are welcome to propose a patch on top of this one if you feel
you can make things cleaner.  The approach of adding a parameter to
con_blank() is Linus idea btw :)

I didn't add a separate function as that would have made the butchering of
drivers/char/vt beyond what I want to deal with in 2.6.