ARM: OMAP3: board-generic: Add missing omap3_init_late

The .init_late callback for OMAP3 has been missing for DT
builds, which causes a lot of late PM initializations to
be missed in turn.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>