cpu-common: Have a ram_addr_t of uint64 with Xen. In Xen case, memory can be bigger than the host memory. that mean a 32bits host (and QEMU) should be able to handle a RAM address of 64bits. Signed-off-by: Anthony PERARD <anthony.perard@citrix.com> Signed-off-by: Alexander Graf <agraf@suse.de>