powerpc/rtas: avoid device tree lookups 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 v6.0.17 by commit 698e682c849e356fb47a8be47ca8baa817cf31e0. For more details please see the references link.