This adds a limit on how much of the framebuffer is ioremap'ed by
radeonfb, thus enabling it to work with 128Mb VRAM or more on an x86
with 900Mb of lowmem in the linear mapping.

It also adds a significant amount of debug messages and adds a CONFIG
option to enable the debugging output, that should help with diagnosing
new problems. Among others, it dumps the connector info as I understand
them (so far, they give "strange" informations on laptops, I need more
data on more various laptops to see if there's a pattern I can really use
to figure out on which connector the LVDS is)

Regarding the "lid closed at boot", ultimately, we may want to default
to the VGA output in those cases, though I'm not sure what logic to use
here. Maybe we could standardize some way for the platform to provide
this "environment" information to the driver, but i wouldn't rely on it.

More reliably, if we can find out that there is an LVDS output, and
LVDS is disabled, just ignore the flat panel...

We could assume any mobility chip has LVDS, which is true, but that would
still cause a problem for laptops with an additional DVI output (only
Macs so far afaik).