net: Add the missing option declaration of "vhostforce"

Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

net.c

@@ -968,6 +968,10 @@ static const struct {
                 .name = "vhostfd",
                 .type = QEMU_OPT_STRING,
                 .help = "file descriptor of an already opened vhost net device",
+            }, {
+                .name = "vhostforce",
+                .type = QEMU_OPT_BOOL,
+                .help = "force vhost on for non-MSIX virtio guests",
         },
 #endif /* _WIN32 */
             { /* end of list */ }