ACPICA: Interpreter: Begin deprecation of Unload operator

The Unload AML operator is no longer supported for the reasons below.
An AE_NOT_IMPLEMENTED exception is returned.
    1) A correct implementation on at least some hosts may not be possible.
    2) Other ACPI implementations do not correctly/fully support it.
    3) It requires host device driver support which is not known to exist.
        (To properly support namespace unload out from underneath.)
    4) This AML operator has never been seen in the field.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Erik Schmauss <erik.schmauss@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/exconfig.c

@@ -489,6 +489,17 @@ acpi_status acpi_ex_unload_table(union acpi_operand_object *ddb_handle)
 	 */
 	ACPI_WARNING((AE_INFO, "Received request to unload an ACPI table"));
 
+	/*
+	 * May 2018: Unload is no longer supported for the following reasons:
+	 * 1) A correct implementation on some hosts may not be possible.
+	 * 2) Other ACPI implementations do not correctly/fully support it.
+	 * 3) It requires host device driver support which does not exist.
+	 *    (To properly support namespace unload out from underneath.)
+	 * 4) This AML operator has never been seen in the field.
+	 */
+	ACPI_EXCEPTION((AE_INFO, AE_NOT_IMPLEMENTED,
+			"AML Unload operator is not supported"));
+
 	/*
 	 * Validate the handle
 	 * Although the handle is partially validated in acpi_ex_reconfiguration()