PPS: convert class code to use dev_groups

The dev_attrs field of struct class is going away soon, dev_groups
should be used instead.  This converts the pps class code to use the
correct field.

Cc: Rodolfo Giometti <giometti@enneenne.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/pps/pps.c

@@ -406,7 +406,7 @@ static int __init pps_init(void)
 		pr_err("failed to allocate class\n");
 		return PTR_ERR(pps_class);
 	}
-	pps_class->dev_attrs = pps_attrs;
+	pps_class->dev_groups = pps_groups;
 
 	err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
 	if (err < 0) {