powerpc/pci: Fix getphbnumber() locking
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 v5.19.4 by commit 90f195c01a2e8d8da6281791617e21109719c981, it was introduced in version v5.19.2 by commit f35c7f506fb96a23a1961c7314c5931ec8bc473e. For more details please see the references link.