vhost: implement cuse memory table

vhost: implement cuse memory table

remove set_memory_table ops

vhost-cuse or vhost-user will both implement their own set_memory_region handler.

In current vhost-cuse implementation, guest numa memory isn't supported.
Assume that guest memory is backed by only one file.

Signed-off-by: Huawei Xie <huawei.xie@intel.com>
Signed-off-by: Przemyslaw Czesnowicz <przemyslaw.czesnowicz@intel.com>