dell-wmi: mask off upper bytes of event response

In debugging with some future machines that actually contain BIOS level
support for dell-wmi, I've determined that the upper half of the data that
comes back from wmi_get_event_data may sometimes contain extra information
that isn't currently relevant when pulling scan codes out of the data.
This causes dell-wmi to improperly respond to these events.

Signed-off-by: Mario Limonciello <mario_limonciello@dell.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/platform/x86/dell-wmi.c

@@ -122,7 +122,12 @@ static void dell_wmi_notify(u32 value, void *context)
 
 	if (obj && obj->type == ACPI_TYPE_BUFFER) {
 		int *buffer = (int *)obj->buffer.pointer;
-		key = dell_wmi_get_entry_by_scancode(buffer[1]);
+		/*
+		 *  The upper bytes of the event may contain
+		 *  additional information, so mask them off for the
+		 *  scancode lookup
+		 */
+		key = dell_wmi_get_entry_by_scancode(buffer[1] & 0xFFFF);
 		if (key) {
 			input_report_key(dell_wmi_input_dev, key->keycode, 1);
 			input_sync(dell_wmi_input_dev);