Input: uinput - fix returning EPOLLOUT from uinput_poll

Always return EPOLLOUT from uinput_poll to allow polling /dev/uinput
for writable state.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Link: https://lore.kernel.org/r/20191204025014.5189-1-marcel@holtmann.orgSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/misc/uinput.c

@@ -695,7 +695,7 @@ static __poll_t uinput_poll(struct file *file, poll_table *wait)
 	if (udev->head != udev->tail)
 		return EPOLLIN | EPOLLRDNORM;
 
-	return 0;
+	return EPOLLOUT | EPOLLWRNORM;
 }
 
 static int uinput_release(struct inode *inode, struct file *file)