x86/xen: Add xenpvrestoreregsandreturntousermode()
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 v5.15.7 by commit e19a07833960e50ba6e969751291483d4e94a024, it was introduced in version v4.15 by commit 7f2590a110b837af5679d08fc25c6227c5a8c497. For more details please see the references link.