GSD-2023-1001049 selftests/powerpc: Fix resource leaks

selftests/powerpc: Fix resource leaks 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 v5.15.86 by commit 8de2c29db68b3d7e4cd2661059085b14c450763...