QEMU mandates the VIRTIO_PMEM address is aligned to a pagesize.
This is a very reasonable requirement. So much so, that it
deserves to be in hypervisor agnostic validation code
(virDomainMemoryDefValidate()). Not that any other hypervisor
would support VIRTIO_PMEM yet. But even if they did, this would
surely be still valid.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Ján Tomko <jtomko@redhat.com>