If we initialize *all* of the region registers to be non-identity mapped we 
can catch a few more bugs that might be covered up by whatever their previous 
state was.  This patch sets them all up to use VHPT (i.e. non alt-tlb) 
address translation.  It already helped me find one bug in the sn2 
initialization code.

Signed-off-by: Jesse Barnes <jbarnes@sgi.com>

Thanks,
Jesse