remote: fix set-branches usage

Bad copy-paste.

Otherwise "git remote set-branches" without necessary argument
will result in an error message and help for set-url subcommand.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/remote.c

@@ -1336,7 +1336,7 @@ static int set_branches(int argc, const char **argv)
 			     builtin_remote_setbranches_usage, 0);
 	if (argc == 0) {
 		error("no remote specified");
-		usage_with_options(builtin_remote_seturl_usage, options);
+		usage_with_options(builtin_remote_setbranches_usage, options);
 	}
 	argv[argc] = NULL;