ARM: dts: omap3-igep: Update onenand node timings

Update node timings to be compatible with actual chip used -
gpmc_cs_show_timings utilized to dump values.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Roger Quadros <rogerq@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>