From Benjamin Herrenschmidt <benh@kernel.crashing.org>:

This adds the Kconfig option for the PowerMac IDE driver "LED" feature
(using the laptop's front LED as a disk activity indicator).  It also
adds a small bit to ide-probe.c that was missing from Jens patch when he
added the activity function infrastructure.  He did add the hwif field,
but not the code to actually enable it.