leds: convert IDE trigger to common disk trigger

This patch converts the IDE specific LED trigger to a generic disk
activity LED trigger. The libata core is now a trigger source just
like before the IDE disk driver. It's merely a replacement of the
string ide by disk.

The patch is taken from http://dev.gentoo.org/~josejx/ata.patch and is
widely used by any ibook/powerbook owners with great satisfaction.
Likewise, it is very often used successfully on different ARM platforms.

Unlike the original patch, the existing 'ide-disk' trigger is still
available for backward compatibility. That reduce the amount of patches
in affected device trees out of the mainline kernel. For further
development, the new name 'disk-activity' should be used.

Cc: Joseph Jezak <josejx@gentoo.org>
Cc: Jörg Sommer <joerg@alea.gnuu.de>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Stephan Linz <linz@li-pro.net>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

drivers/ata/libata-core.c

@@ -69,6 +69,7 @@
 #include <asm/unaligned.h>
 #include <linux/cdrom.h>
 #include <linux/ratelimit.h>
+#include <linux/leds.h>
 #include <linux/pm_runtime.h>
 #include <linux/platform_device.h>
 
@@ -5072,6 +5073,9 @@ void ata_qc_complete(struct ata_queued_cmd *qc)
 {
 	struct ata_port *ap = qc->ap;
 
+	/* Trigger the LED (if available) */
+	ledtrig_disk_activity();
+
 	/* XXX: New EH and old EH use different mechanisms to
 	 * synchronize EH with regular execution path.
 	 *