vhost: fix crash by removing device when requested
vhost: fix crash by removing device when requested

This patch fixes the segfault issue in the case vhost receives
new VHOST_SET_MEM_TABLE message without VHOST_VRING_GET_VRING_BASE
(which we uses as the stop message).

Signed-off-by: Huawei Xie <3b3be4428106761300a2ee559c9f71ecdb091553@intel.com>
Acked-by: Tommy Long <75d77ca60f4be7663a52b690bb7457a7606983f9@intel.com>

mixja/dpdk,john-mcnamara-intel/dpdk,venkynv/dpdk-mirror,mixja/dpdk,venkynv/dpdk-mirror,john-mcnamara-intel/dpdk,msune/dpdk,tsphillips/dpdk-fork,mixja/dpdk,venkynv/dpdk-mirror,msune/dpdk,venkynv/dpdk-mirror,msune/dpdk,msune/dpdk,tsphillips/dpdk-fork,john-mcnamara-intel/dpdk,tsphillips/dpdk-fork,tsphillips/dpdk-fork,john-mcnamara-intel/dpdk,mixja/dpdk