ACPI: PM: s2idle: Refactor common code

Refactor common code to prepare for upcoming changes.
 * Remove unused struct.
 * Print error before returning.
 * Frees ACPI obj if _DSM type is not as expected.
 * Treat lps0_dsm_func_mask as an integer rather than character
 * Remove extra out_obj
 * Move rev_id

Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Pratik Vishwakarma <Pratik.Vishwakarma@amd.com>
Tested-by: Julian Sikorski <belegdol@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>