Do not use extended sleep registers unless HW-reduced bit is set.

Previous implementation incorrectly used the ACPI 5.0 extended sleep
registers if they were simply populated. This caused problems on some
non-HW-reduced machines. As per the ACPI spec,
they should only be used if the HW-reduced bit is set.
Lv Zheng, ACPICA BZ 1020.

source/components/hardware/hwxfsleep.c

@@ -339,13 +339,14 @@ AcpiHwSleepDispatch (
 
 
 #if (!ACPI_REDUCED_HARDWARE)
-
     /*
      * If the Hardware Reduced flag is set (from the FADT), we must
-     * use the extended sleep registers
+     * use the extended sleep registers (FADT). Note: As per the ACPI
+     * specification, these extended registers are to be used for HW-reduced
+     * platforms only. They are not general-purpose replacements for the
+     * legacy PM register sleep support.
      */
-    if (AcpiGbl_ReducedHardware ||
-        AcpiGbl_FADT.SleepControl.Address)
+    if (AcpiGbl_ReducedHardware)
     {
         Status = SleepFunctions->ExtendedFunction (SleepState);
     }