ACPI: bugfix reporting of event handler status

Introduce a new flag showing whether the event has an event handler/method.

For all the GPEs and Fixed Events,
 1. ACPI_EVENT_FLAG_HANDLE is cleared, it's an "invalid" ACPI event.
 2. Both ACPI_EVENT_FLAG_HANDLE and ACPI_EVENT_FLAG_DISABLE are set,
    it's "disabled".
 3. Both ACPI_EVENT_FLAG_HANDLE and ACPI_EVENT_FLAG_ENABLE are set,
    it's "enabled".
 4. Both ACPI_EVENT_FLAG_HANDLE and ACPI_EVENT_FLAG_WAKE_ENABLE are set,
    it's "wake_enabled".

Among other things, this prevents incorrect reporting of ACPI events
as being "invalid" when it's really just (temporarily) "disabled".

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Len Brown <len.brown@intel.com>

Documentation/ABI/testing/sysfs-firmware-acpi

@@ -89,7 +89,7 @@ Description:
 
 		error - an interrupt that can't be accounted for above.
 
-		invalid: it's either a wakeup GPE or a GPE/Fixed Event that
+		invalid: it's either a GPE or a Fixed Event that
 			doesn't have an event handler.
 
 		disable: the GPE/Fixed Event is valid but disabled.
@@ -117,30 +117,30 @@ Description:
 		and other user space applications so that the machine won't shutdown
 		when pressing the power button.
 		# cat ff_pwr_btn
-		0
+		0	enabled
 		# press the power button for 3 times;
 		# cat ff_pwr_btn
-		3
+		3	enabled
 		# echo disable > ff_pwr_btn
 		# cat ff_pwr_btn
-		disable
+		3	disabled
 		# press the power button for 3 times;
 		# cat ff_pwr_btn
-		disable
+		3	disabled
 		# echo enable > ff_pwr_btn
 		# cat ff_pwr_btn
-		4
+		4	enabled
 		/*
 		 * this is because the status bit is set even if the enable bit is cleared,
 		 * and it triggers an ACPI fixed event when the enable bit is set again
 		 */
 		# press the power button for 3 times;
 		# cat ff_pwr_btn
-		7
+		7	enabled
 		# echo disable > ff_pwr_btn
 		# press the power button for 3 times;
 		# echo clear > ff_pwr_btn	/* clear the status bit */
 		# echo disable > ff_pwr_btn
 		# cat ff_pwr_btn
-		7
+		7	enabled