arm: omap2: n8x0: move i2c devices to DT

By moving i2c devices to DT we can clean up
i2c_board_info and fix a problem with moving
INTC to irq domain where IRQs can be renumbered
on each boot.

Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>