omap: pandora: fix NAND support

Commit d5ce2b65 "omap3630: nand: fix device size to work in polled mode"
changed values for .devsize in nand platform data, now we have to pass
NAND_BUSWIDTH_16 instead of '1' to select 16bit NAND.

Update pandora's platform data accordingly, also specify appropriate
transfer type.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>