Add a new API rte_vhost_async_dma_unconfigure() to unconfigure DMA
vChannels in vhost async data path. Lock protection are also added
to protect DMA vChannel configuration and unconfiguration
from concurrent calls.
Signed-off-by: Xuan Ding <xuan.ding@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>