amd-pstate: Fix memory leak in amd_pstate_epp_cpu_init()

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).

Assisted-by: Claude:claude-opus-4.6 review-prompts/linux
Fixes: f9a378ff6443 ("cpufreq/amd-pstate: Set different default EPP policy for Epyc and Ryzen")
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>