powerpc/rtas: avoid scheduling in rtasosterm()
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 v5.15.87 by commit 7280fdb80bf0fe35d9b799fc7009f2cbe0a397d7. For more details please see the references link.