qemu: fill capabilities for virtiofsd

Run the daemon with --print-capabilities first, to see what it supports.

Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

tests/qemuvhostuserdata/usr/share/qemu/vhost-user/50-qemu-virtiofsd.json

@@ -1,5 +1,5 @@
 {
   "description": "virtiofsd vhost-user-fs",
   "type": "fs",
-  "binary": "/usr/libexec/qemu/vhost-user/test-vhost-user-gpu"
+  "binary": "/usr/libexec/qemu/vhost-user/test-virtiofsd"
 }