vhost: fix missing cache logging NUMA realloc

vhost: fix missing cache logging NUMA realloc

When the guest allocates virtqueues on a different NUMA node
than the one the Vhost metadata are allocated, both the Vhost
device struct and the virtqueues struct are reallocated.

However, reallocating the log cache on the new NUMA node was
not done. This patch fixes this by reallocating it if it has
been allocated already, which means a live-migration is
on-going.

Fixes: 1818a63147fb ("vhost: move dirty logging cache out of virtqueue")
Cc: stable@dpdk.org
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>