Input: add open and close methods for polled devices

Optional open and close methods for preparing and closing
the device.

Signed-off-by: Samu Onkalo <[email protected]>
Signed-off-by: Dmitry Torokhov <[email protected]>
diff --git a/drivers/input/misc/wistron_btns.c b/drivers/input/misc/wistron_btns.c
index a932179..00eb9d6 100644
--- a/drivers/input/misc/wistron_btns.c
+++ b/drivers/input/misc/wistron_btns.c
@@ -1263,7 +1263,7 @@
 	if (!wistron_idev)
 		return -ENOMEM;
 
-	wistron_idev->flush = wistron_flush;
+	wistron_idev->open = wistron_flush;
 	wistron_idev->poll = wistron_poll;
 	wistron_idev->poll_interval = POLL_INTERVAL_DEFAULT;