xen/privcmd: Fix a possible warning in privcmdioctlmmap_resource()
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 v6.0.16 by commit e0c5f1058ed96f2b7487560c4c4cbd768d13d065, it was introduced in version v4.18 by commit 3ad0876554cafa368f574d4d408468510543e9ff. For more details please see the references link.