nvme: avoid segfault in show-topology

The show-topology command currently ends in a segfault for
ENOENT scenarios:

nvme show-topology
Failed to scan topology: No such file or directory
Segmentation fault (core dumped)

Fix this by eliminating the call to nvme_free_tree() since the
cleanup helper is already available here.

Signed-off-by: Martin George <marting@netapp.com>

Author: martin-gpy

nvme.c

@@ -9585,7 +9585,6 @@ static int show_topology_cmd(int argc, char **argv, struct command *command, str
 	err = nvme_scan_topology(r, NULL, NULL);
 	if (err < 0) {
 		nvme_show_error("Failed to scan topology: %s", nvme_strerror(errno));
-		nvme_free_tree(r);
 		return err;
 	}