staging: comedi: do not return -ENOSYS.

fixed coding style issue by replacing ENOSYS
with EIO because it means 'invalid syscall nr'
and nothing else.
Signed-off-by: Ted Chen <tedc.37zngo@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers.c

@@ -820,7 +820,7 @@ int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 			 "driver '%s' does not support attach using comedi_config\n",
 			 driv->driver_name);
 		module_put(driv->module);
-		ret = -ENOSYS;
+		ret = -EIO;
 		goto out;
 	}
 	dev->driver = driv;