wireless: at76c50x: signedness bug in at76_dfu_get_state()

This return holds the number of bytes transfered (1 byte) or a negative
error code.  The type should be int instead of u8.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NPavel Roskin <proski@gnu.org>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/at76c50x-usb.c

@@ -342,7 +342,7 @@ static int at76_dfu_get_status(struct usb_device *udev,
 	return ret;
 }
 
-static u8 at76_dfu_get_state(struct usb_device *udev, u8 *state)
+static int at76_dfu_get_state(struct usb_device *udev, u8 *state)
 {
 	int ret;