bpf_load: add map name to load_maps error message

To help when debugging bpf/xdp load issues, have the load_map()
error message include the number and name of the map that
failed.
Signed-off-by: NShannon Nelson <shannon.nelson@oracle.com>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NSong Liu <songliubraving@fb.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

samples/bpf/bpf_load.c

@@ -284,8 +284,8 @@ static int load_maps(struct bpf_map_data *maps, int nr_maps,
 							numa_node);
 		}
 		if (map_fd[i] < 0) {
-			printf("failed to create a map: %d %s\n",
-			       errno, strerror(errno));
+			printf("failed to create map %d (%s): %d %s\n",
+			       i, maps[i].name, errno, strerror(errno));
 			return 1;
 		}
 		maps[i].fd = map_fd[i];