cpufreq/amd-pstate: Use scope based cleanup for cpufreq_policy refs

cpufreq/amd-pstate: Use scope based cleanup for cpufreq_policy refs

There have been instances in past where refcount decrementing is missed
while exiting a function. Use automatic scope based cleanup to avoid
such errors.

Signed-off-by: Dhananjay Ugwekar <dhananjay.ugwekar@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20250205112523.201101-12-dhananjay.ugwekar@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>