vhost: allocate all data on same node as virtqueue

vhost: allocate all data on same node as virtqueue

This patch saves the NUMA node the virtqueue is allocated
on at init time, in order to allocate all other data on the
same node.

While most of the data are allocated before numa_realloc()
is called and so the data will be reallocated properly, some
data like the log cache are most likely allocated after.

For the virtio device metadata, we decide to allocate them
on the same node as the VQ 0.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>