PS3: Fix memory hotplug

[Paul Mackerras]

Benjamin Herrenschmidt writes:

> When you do an lmb_add you should probably also do an lmb_analyze to
> update the total memory count etc...
> 
> That leads to some interesting issues such as the LMB stuff wasn't
> really meant to be dynamically modified after boot, and thus the kernel
> has no locks in there. That can be an issue...
> 
> Paul, any thoughts here ? Should we add a lock ? That would mean being
> careful as the LMB stuff can be called very early, and spinlock wants
> things like PACA and possibly lockdep to be around.. 

Either that, or we give in and use iomem_resource to track where
system RAM is, as well as the other things in the physical address
space, like other architectures do...

Paul.