block: Fix the maximum minor value is blkallocext_minor()
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v5.15.33 by commit 5b9ac3727e4abb11c9cfbe9c0781fc05dfdd7cfb, it was introduced in version v5.11 by commit 22ae8ce8b89241c94ac00c237752c0ffa37ba5ae. For more details please see the references link.