HID: input: call input_sync() when automatically releasing a key

We need to emit EV_SYN/SYN_REPORT between key press and release, otherwise
userspace is allowed to "swallow" the event.

[jkosina@suse.com: Dmitry says that he's observing this behavior with
 Plantronics headset]
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

drivers/hid/hid-input.c

@@ -1163,8 +1163,11 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct
 
 	input_event(input, usage->type, usage->code, value);
 
-	if ((field->flags & HID_MAIN_ITEM_RELATIVE) && (usage->type == EV_KEY))
+	if ((field->flags & HID_MAIN_ITEM_RELATIVE) &&
+	    usage->type == EV_KEY && value) {
+		input_sync(input);
 		input_event(input, usage->type, usage->code, 0);
+	}
 }
 
 void hidinput_report_event(struct hid_device *hid, struct hid_report *report)