net: fix OptsVisitor memory leak

Fixes 96a1616("qapi-dealloc: Reduce use outside of generated code")
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
diff --git a/net/net.c b/net/net.c
index f8b1e00..0ad6217 100644
--- a/net/net.c
+++ b/net/net.c
@@ -1077,6 +1077,7 @@
     }
 
     error_propagate(errp, err);
+    opts_visitor_cleanup(ov);
     return ret;
 }