omap3: add support for NAND on zoom2 board

This patch adds NAND support to ZOOM2 board.

Signed-off-by: Sukumar Ghorai <s-ghorai@ti.com>
Signed-off-by: Vimal Singh <vimalsingh@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>