ARM: OMAP2+: Make n8x0 behave better with device tree based booting

Initialize some devices using a late_initcall and test for
the device tree based booting for some devices.

This way we can keep things working for legacy platform
devices when booted with device tree.

Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Tony Lindgren <tony@atomide.com>