cpufreq: amd-pstate: fix memory leak on CPU EPP exit

In the Linux kernel, the following vulnerability has been resolved: cpufreq: amd-pstate: fix memory leak on CPU EPP exit The cpudata memory from kzalloc() in amd_pstate_epp_cpu_init() is not freed in the analogous exit function, so fix that. [ rjw: Subject and changelog edits ]