libxc: allocate memory with vNUMA information for HVM guest

libxc: allocate memory with vNUMA information for HVM guest

The algorithm is more or less the same as the one used for PV guest.
Libxc gets hold of the mapping of vnode to pnode and size of each vnode
then allocate memory accordingly.

And then the function returns low memory end, high memory end and mmio
start to caller. Libxl needs those values to construct vmemranges for
that guest.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Elena Ufimtseva <ufimtseva@gmail.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>