soc: aspeed: Fix snoop_file_poll()'s return type

snoop_file_poll() is defined as returning 'unsigned int' but the
.poll method is declared as returning '__poll_t', a bitwise type.

Fix this by using the proper return type and using the EPOLL
constants instead of the POLL ones, as required for __poll_t.

Link: https://lore.kernel.org/r/20191121051851.268726-1-joel@jms.id.au
Fixes: 3772e5da ("drivers/misc: Aspeed LPC snoop output using misc chardev")
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Olof Johansson <olof@lixom.net>

drivers/soc/aspeed/aspeed-lpc-snoop.c

@@ -97,13 +97,13 @@ static ssize_t snoop_file_read(struct file *file, char __user *buffer,
 	return ret ? ret : copied;
 }
 
-static unsigned int snoop_file_poll(struct file *file,
+static __poll_t snoop_file_poll(struct file *file,
 				    struct poll_table_struct *pt)
 {
 	struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file);
 
 	poll_wait(file, &chan->wq, pt);
-	return !kfifo_is_empty(&chan->fifo) ? POLLIN : 0;
+	return !kfifo_is_empty(&chan->fifo) ? EPOLLIN : 0;
 }
 
 static const struct file_operations snoop_fops = {