numa: add -numa node,memdev= option

This option provides the infrastructure for binding guest NUMA nodes
to host NUMA nodes.  For example:

 -object memory-ram,size=1024M,policy=bind,host-nodes=0,id=ram-node0 \
 -numa node,nodeid=0,cpus=0,memdev=ram-node0 \
 -object memory-ram,size=1024M,policy=interleave,host-nodes=1-3,id=ram-node1 \
 -numa node,nodeid=1,cpus=1,memdev=ram-node1

The option replaces "-numa node,mem=".

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>

MST: conflict resolution