ARM: dts: N900: fix onenand timings

ARM: dts: N900: fix onenand timings

Commit 062f82c51112 ("mtd: onenand: omap2: Configure driver from DT")
started using DT specified timings for GPMC, and as a result the
OneNAND stopped working on N900 as we had wrong values in the DT.
Fix by updating the values to bootloader timings that have been tested
to be working on Nokia N900 with OneNAND manufacturers: Samsung,
Numonyx.

Fixes: 062f82c51112 ("mtd: onenand: omap2: Configure driver from DT")
Signed-off-by: Arthur Demchenkov <spinal.by@gmail.com>
Tested-by: Merlijn Wajer <merlijn@wizzup.org>
Reviewed-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>