ACPI: PM: s2idle: Enable Low-Power S0 Idle MSFT UUID for non-AMD systems

Systems based on Intel platforms that use the MSFT UUID for Low-Power S0
Idle (LPS0) have started to ship, so allow the kernel to use the MSFT
UUID in the non-AMD case too, but in that case make it avoid evaluating
the same _DSM function for two different UUIDs and prioritize the MSFT
one.

While at it, combine two MSFT _DSM function mask checks in
acpi_s2idle_restore_early() so as to make it reflect the
acpi_s2idle_prepare_late() flow more closely and adjust the
Modern Standby entry and exit comments slightly.

Non-AMD systems that do not support MSFT UUID for Low-power S0 Idle are
not expected to be affected by this change in any way.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>