ACPI: PM: s2idle: Prevent spurious SCIs from waking up the system

If the platform triggers a spurious SCI even though the status bit
is not set for any GPE when the system is suspended to idle, it will
be treated as a genuine wakeup, so avoid that by checking if any GPEs
are active at all before returning 'true' from acpi_s2idle_wake().

Link: https://bugzilla.kernel.org/show_bug.cgi?id=206413
Fixes: 56b99184

 ("PM: sleep: Simplify suspend-to-idle control flow")
Reported-by: Tsuchiya Yuto <kitakar@gmail.com>
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>