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 v5.10.163 by commit 46026bb057c35f5bb111bf95e00cd8366d2e34d4, it was introduced in version v4.18 by commit 3ad0876554cafa368f574d4d408468510543e9ff. For more details please see the references link.