Remove use after free in corosync_main_config_set in error path

Signed-off-by: Steven Dake <sdake@redhat.com>
Reviewed-by: Jan Friesse <jfriesse@redhat.com>

exec/mainconfig.c

@@ -222,7 +222,6 @@ static int corosync_main_config_format_set (
 	return (0);
 
 parse_error:
-	free(value);
 	*error_string = error_reason;
 
 	return (-1);