platform/x86/amd/pmc: Fix LPS0 and debugfs leaks when STB init fails

Summary

In the Linux kernel, the following vulnerability has been resolved: platform/x86/amd/pmc: Fix LPS0 and debugfs leaks when STB init fails amd_pmc_probe() registers the LPS0 s2idle handler with acpi_register_lps0_dev() and creates the driver's debugfs directory before calling amd_stb_s2d_init(), which is the last step in probe that can fail. When amd_stb_s2d_init() fails (for example the S2D telemetry region cannot be ioremapped on a long-running system, or the SMU rejects the S2D setup) the error path only calls pci_dev_put() and returns. This leaves amd_pmc_s2idle_dev_ops on the global lps0_s2idle_devops_head list and leaks the debugfs directory, while the devm-managed resources backing the handler are torn down. Reloading the module then walks the corrupted list in acpi_register_lps0_dev() and hits: list_add corruption. next->prev should be prev, but was NULL. kernel BUG at lib/list_debug.c:29! acpi_register_lps0_dev+0x44/0x80 amd_pmc_probe+0x224/0x380 [amd_pmc] platform_probe+0x67/0x90 Even without a reload, the stale registration means the next s2idle transition calls into torn-down driver state. Unwind the debugfs directory and the LPS0 registration on the amd_stb_s2d_init() error path. acpi_unregister_lps0_dev() is safe to call unconditionally here: it is guarded on the same conditions as acpi_register_lps0_dev(), which is exactly what amd_pmc_remove() already relies on.