platform/x86/amd: pmf: Use device managed allocations

In the Linux kernel, the following vulnerability has been resolved: platform/x86/amd: pmf: Use device managed allocations If setting up smart PC fails for any reason then this can lead to a double free when unloading amd-pmf. This is because dev->buf was freed but never set to NULL and is again freed in amd_pmf_remove(). To avoid subtle allocation bugs in failures leading to a double free change all allocations into device managed allocations.