ACPI / CPPC: Don't return on CPPC probe failure

It is still possible to continue even CPPC data is invalid or missing.

Suggested-by: Alexey Klimov <alexey.klimov@arm.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>