vhost: fix missed unlock
vhost: fix missed unlock

CID 107113 (#1 of 1): Missing unlock (LOCK)5. missing_unlock: Returning
without unlocking pfdset->fd_mutex.
Fixes: fbf7e07ca142 ("vhost: add select based event driven processing")

Signed-off-by: Huawei Xie <3b3be4428106761300a2ee559c9f71ecdb091553@intel.com>
Acked-by: John McNamara <af31595c36a4239b9676e9b3a777d3e2f15a6c4d@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk