ARM: OMAP1: osk5912: LED trigger update for CF

Help OSK work better with root-on-CF, by having one of the LEDs
use the "ide-disk" trigger (to kick in during CF I/O).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>