amd-pstate: Fix memory leak in amd_pstate_epp_cpu_init()

In the Linux kernel, the following vulnerability has been resolved:

amd-pstate: Fix memory leak in amd_pstate_epp_cpu_init()

On failure to set the epp, the function amd_pstate_epp_cpu_init() returns with an error code without freeing the cpudata object that was allocated at the beginning of the function.

Ensure that the cpudata object is freed before returning from the function.

This memory leak was discovered by Claude Opus 4.6 with the aid of Chris Mason's AI review-prompts (https://github.com/masoncl/review-prompts/tree/main/kernel).