We have code to allocate big chunks of linear memory on bootup for later use.
This code is currently used for RMA allocation, but can be useful beyond that
extent.

Make it generic so we can reuse it for other stuff later.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Acked-by: NPaul Mackerras <paulus@samba.org>
Signed-off-by: NAvi Kivity <avi@redhat.com>