ARM: dts: cm-t3x: add NAND support

CM-T3517, CM-T3530 and CM-T3730 features NAND storage chip connected to
GPMC bus.

Add GPMC DT entry into the root DT file omap3-cm-t3x.dtsi, common for
all three modules.

NAND timings are calculated to be safe for CM-T3x devices as it works
now in non DT boot (in this case the timings are updated by U-Boot).

Update GPMC ranges in boards DT files to include all connected devices.

Signed-off-by: Dmitry Lifshitz <lifshitz@compulab.co.il>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
Acked-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>