ACPI: Use GPE reference counting to support shared GPEs

To fix a bug and address the reviewers' comments regarding the ACPI
GPE refcounting patch, do the following additional changes:

o Remove the second argument of acpi_ev_enable_gpe(),
  'write_to_hardware', because it is not necessary any more.

o Add the "bad parameter" test against 'type' in
  acpi_enable_gpe() and acpi_disable_gpe().

o Make acpi_enable_gpe() only check 'status' for runtime GPEs if
  acpi_ev_enable_gpe() was actually called.

o Make acpi_disable_gpe() return 'status' returned by
  acpi_ev_disable_gpe() and fix a bug where ACPI_GPE_TYPE_WAKE
  and ACPI_GPE_TYPE_RUNTIME were exchanged by mistake.

o Add comments explaining why acpi_set_gpe() is used by the ACPI EC
  driver.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/acpi/acpica/acevents.h b/drivers/acpi/acpica/acevents.h
index 197aa4f..4ced54f 100644
--- a/drivers/acpi/acpica/acevents.h
+++ b/drivers/acpi/acpica/acevents.h
@@ -78,9 +78,7 @@
 acpi_status
 acpi_ev_update_gpe_enable_masks(struct acpi_gpe_event_info *gpe_event_info);
 
-acpi_status
-acpi_ev_enable_gpe(struct acpi_gpe_event_info *gpe_event_info,
-		   u8 write_to_hardware);
+acpi_status acpi_ev_enable_gpe(struct acpi_gpe_event_info *gpe_event_info);
 
 acpi_status acpi_ev_disable_gpe(struct acpi_gpe_event_info *gpe_event_info);