conf: fix vsock memory leaks
Introduced by:
commit d4abb7b45d48aba77c2464dbea95f02a43a60834
conf: introduce <vsock> element
commit b8b42ca036adbfaac1741c8efe389cd1403e220b
qemu: add support for vhost-vsock-pci
Signed-off-by: Ján Tomko <jtomko@redhat.com>