ARM: dts: omap3430-sdp: Revert to using software ECC for NAND

For v3.14 and prior, 1-bit Hamming code ECC via software was used
for NAND on this board.
Commit c06c5270

 in v3.15 changed the behaviour
to use 1-bit Hamming code via Hardware using a different ECC layout
i.e. (ROM code layout) than what is used by software ECC.

This ECC layout change causes NAND filesystems created in v3.14
and prior to be unusable in v3.15 and later. So revert back to
using software ECC scheme.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>