rtc: switch to using is_visible() to control sysfs attributes

Instead of creating wakealarm attribute manually, after the device has been
registered, let's rely on facilities provided by the attribute groups to
control which attributes are visible and which are not. This allows to
create all needed attributes at once, at the same time that we register RTC
class device.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
index de7707f..de86578 100644
--- a/drivers/rtc/class.c
+++ b/drivers/rtc/class.c
@@ -202,6 +202,7 @@
 	rtc->max_user_freq = 64;
 	rtc->dev.parent = dev;
 	rtc->dev.class = rtc_class;
+	rtc->dev.groups = rtc_get_dev_attribute_groups();
 	rtc->dev.release = rtc_device_release;
 
 	mutex_init(&rtc->ops_lock);
@@ -240,7 +241,6 @@
 	}
 
 	rtc_dev_add_device(rtc);
-	rtc_sysfs_add_device(rtc);
 	rtc_proc_add_device(rtc);
 
 	dev_info(dev, "rtc core: registered %s as %s\n",
@@ -271,7 +271,6 @@
 	 * Remove innards of this RTC, then disable it, before
 	 * letting any rtc_class_open() users access it again
 	 */
-	rtc_sysfs_del_device(rtc);
 	rtc_dev_del_device(rtc);
 	rtc_proc_del_device(rtc);
 	device_del(&rtc->dev);
@@ -360,7 +359,6 @@
 	}
 	rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
 	rtc_dev_init();
-	rtc_sysfs_init(rtc_class);
 	return 0;
 }