ACPI/PPTT: Add support for ACPI 6.3 thread flag

Commit bbd1b70639f785a970d998f35155c713f975e3ac upstream.

ACPI 6.3 adds a flag to the CPU node to indicate whether
the given PE is a thread. Add a function to return that
information for a given linux logical CPU.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Robert Richter <rrichter@marvell.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Will Deacon <will@kernel.org>
[jpg: backport for 4.19, replace acpi_pptt_warn_missing()]
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>